Milk allergy???? Please help

Hi, im gonna make it short as baby has been unwell, Savannah was diagnosed with silent reflux at 3 months old, she is 6 months now. After trying comfort milk, cow and gate, aptamil, i decided to put lo on soya milk which she drinks ok, much better than the other milks mentioned. I tried her on sma follow on milk the other day, since then she has showed signs of allergic reactions, e.g. wheezing, coughing, severe stomach pains,hard tummy, not sleeping, fever, rash on her cheeks, flatulence, loose stools. she is also like this when i have tried to give her rusks, baby rice, and chocolate pudding. The pediatricians are useless and havent tried to find out anything, just gave her meds for reflux. The G.P tested her poo but it came back negative, she is 25 weeks old and 12lbs 12. Any ideas???? Im at breaking point again. ;(( Thankyou in advance. xxxx