Bethany, now two and a half, does all the things other children do and the doctors hope her condition will right itself as she grows older. But she becomes breathless easily and her parents fear there may be a link between her illness and the nearby tip.
People in Micklefield have campaigned against the tip, saying it causes terrible smells and that their houses are full of flies, even in winter. They say the rubbish is piled so high it blocks the light from houses just yards away on the other side of a road.
"It's horrendous," Mrs Tomkinson said. "It was only quite recently that I heard on the news about these problems. You can never prove it, but it does make you wonder.
"I think in 10 or 15 years they will turn round and say they were wrong to put the tip there."
Mrs Tomkinson is expecting her second child in May, and so far there is no indication of any problem.
Kerry Huntley spent the last three months before the birth of her first child wondering whether her daughter would survive.
Cleo was born with gastroschisis, which was highlighted by a scan, and her intestines and stomach were outside her abdomen when she was delivered by Caesarean section a month early.
"We couldn't plan anything. I felt like I had something growing inside me but I couldn't bond," said Mrs Huntley. "She was six weeks in hospital before she came home and even then she only weighed five or six pounds."
Fortunately for the Huntleys, an operation to correct the defect was successful and Cleo is now a healthy seven-year-old.
Three years after the birth they heard that an unusually high number of children born near the Nant-y-Gwyddon landfill site near Tonypandy in the Rhondda Valley, South Wales, had similar problems.
Although there is no proof that Cleo's ailment was caused by the site, just a quarter of a mile from the Huntleys' home, they suspect there might be a link.
Families in the area have complained that the smell from the site makes them nauseous, and they are campaigning for the tip to be closed.