Hours after baby Lilly was born, her mother Jane Bell, from South London, knew something was wrong.
Lilly's face was red and swollen because of her allergy
Jane tried breastfeeding, like many mums, but Lilly struggled to feed.
Jane persevered and, on the advice of medical staff, also introduced formula milk feeds in a bottle to help Lilly get the nutrients she needed.
But things went from bad to worse.
Jane recalls: "Her face was really shiny and red and she refused to feed.
"What she was getting down she would throw up again.
"Her stools were really pungent and runny. She constantly had diarrhoea. Other times they were like jelly. Her whole bottom was peeling where it was red raw.
"She also had a rasping to her breathing, like she wasn't getting enough air."
When Lilly was eight weeks old, Jane took her to a health visitor who told her that Lilly was not gaining enough weight.
Over the next weeks she went back and forth to the GP, who advised her that Lilly most likely had a stomach upset - gastroenteritis.
Jane began to notice that when Lilly stopped having her bottle feeds because of her diarrhoea and vomiting, her symptoms started to improve.
"But as soon as I reintroduced the milk she would get really sick again," Jane explained.
This went on for about five months, then Lilly's GP referred her to see a hospital specialist.
Lilly was switched to soya milk, but this did not help.
"She just got worse and worse. Then when she was eight months she got more and more sleepy and then one day I just couldn't wake her up."
Lilly was rushed to hospital and when there the doctors looking after her suggested that she might have an allergy to the feeds she had been having.
In the UK, infant formulae and follow-on formulae are based on cows' milk protein, hydrolysed protein or soya protein.
They prescribed Lilly a special low-allergy or hypoallergenic formula milk.
"Within two to three weeks the change was phenomenal. She was so much better.
"But it took a long time for her immune system to calm down."
Lilly is now healthy and nine years old, but she still has to be careful about what she eats. She is allergic to dairy products, eggs, soya and nuts.
She has to take tablets every day to keep her immune system in check and needs to carry an emergency injection of adrenaline around with her at all times in case she has a severe reaction to something she eats.
Jane advised any parents who are concerned that their infant might have a food allergy to seek medical advice.
She added: "And if you are not happy with the advice, get a second opinion
"It is hard for GPs to diagnose. The symptoms are not always the same. But it is easy to track and simple to test. Try stopping the milk or food for a week or so and see if it helps."