They thought I was just a fussy new mum at first. "Don't worry Mrs Jones," they said, "all babies make that whimpering noise." All babies are sometimes sick when they have been fed, they said. Don't worry, three different doctors said, repeatedly. Your little boy looks fine.

And I tried not to worry. I tried to do as they said. I thought they knew best. But I think I knew then, even when they were telling me that everything would be all right, that it wasn't.

Toby never cried as a baby. He never cooed. He never made any baby sounds.

He'd lie in his little cot, being repeatedly sick, milk coming out of his nose and mouth.

They said it was reflux, and I wanted to believe they were right.

Toby came home and he just wouldn't feed. He wouldn't take the teat in his mouth. He would drink an ounce an hour. But because I would feed him little and often, his weight was ok.

It didn't last. At six months, it stopped.

The weight fell off him. He had to be fed with tubes in his nose. David, my husband, had to do that. I couldn't do it.

I was a physical wreck by this time. I wasn't sleeping. I was always checking to see if he was asleep, that he wasn't choking. Finally, they believed me. Toby was ill.

But what was it? We spent more time at the Leicester Royal Infirmary than we did at home. But they still didn't know what it was.

When he was eight months old, a passing neurologist looked at him and said straight away: "That baby has myasthenia."

Apparently, the left side of Toby's face was droopy – it was so slight, we didn't notice it. But he did. And he knew what it meant.

Congenital Myasthenia Syndrome is a hereditary condition which leads to abnormal muscle weakness and excessive tiredness.

It's rare, very rare, and affects just one or two children in every million.

I have the gene and my husband Dave has the gene. We were tested after Toby was diagnosed. We had no idea.

And yet, even then, we only have a one-in-four chance of having a baby with the condition.

This faulty gene affects the transmission of messages from nerve to muscle.

The muscles tire easily, making repetitive movements, like walking – and in Toby's case, eating and talking – difficult or impossible.

Some children struggle to breathe. Some can't keep their eyes open.

Thankfully, that neurologist, Dr Jay, became Toby's neurologist. He's brilliant. He prescribed Toby medication; a crushed tablet he has to take eight times a day, every three hours, day and night.

It's a strong drug – he's on the dose for a 12-year-old – but it helps to transmit those messages from nerve to muscle.

The difference was immediate and incredible. Toby started drinking properly, putting on weight. For the first time, at nine months old, he drank three ounces of milk in one go.

He'd never done that before. He started smiling. He cried. I never thought I'd be pleased to hear my baby cry. He was blossoming.

Today, Toby is three and he's doing well. He tires easily and all of his food has to be pureed, but he's doing well.

I discovered I was pregnant again early this year. It was a surprise. We decided to go ahead with the pregnancy. We knew the risks but we didn't want Toby to be an only child.

If anything happens to me or David, I wanted to know there was someone else there for him.

Jessica was born 10 weeks ago, on August 12. They gave me the opportunity to have a test to see if she also had it.

I couldn't do it. By then I was 16 weeks pregnant. I felt she was part of me. There was a huge risk that the test would lead to miscarriage.

I couldn't bear that.

And if the test was positive... Would I have been able to terminate the pregnancy? I'm not sure that I could.

Also, if the test was positive, I didn't want to carry her for another five, six months knowing that I'd be giving birth to another baby with the same problems as Toby.

So I had a normal pregnancy and I hoped for the best. I have no regrets. None whatsoever.

Jessica was born 10 weeks ago, a caesarian section like Toby. She looked healthy. I thought she might be ok.

She was born at the Leicester General Hospital. They took a sample from her umbilical cord and there was actually a taxi waiting outside the hospital to take the sample to a lab at the John Radcliffe Hospital in Oxford.

They had to grow it before they could test it and it took a while for the results to come through. I fed her, I winded her. On one occasion, she was sick. The milk came from her mouth and nostrils.

I took her home. She seemed well. She had a strong cry. She was feeding from the bottle. We dared to hope that she might be all right.

Three weeks later the results came through: she had it, too.

I was heartbroken. Both of my kids had this nasty illness and I knew that they would have it for life.

I'm 28, and I sometimes catch myself thinking: Did I do the right thing? Am I ready for this?

My life, Dave's life, their lives: it will be hard work from here. We don't have a plan. We just plan to take it one day at a time.

I'm determined, though, that we will deal with it, that it won't take over our lives.

I have two brilliant children and I love them dearly. I don't have any regrets, none whatsoever.

Last year, Melissa and another mum set up a support group for families with myasthenic children.

"It started off quite small, but now we have around 30 families involved. It's good to support each other and share information, but it also helps to raise awareness of a condition that few people know about."

www.myasthenickids.org

Melissa Jones was talking to Lee Marlow