Help please-How do i know if its a milk allergy

*DS is 4 moths old
so DS has been not feeling good for over a week now. Low grade fever and a definite cold. Around the same time the cold started, he was having intestinal things like gas and spitting up a lot. So i called the ped and he said give him soy b/c he may have a milk allergy. I didn't feel comfortable giving soy b/c i wasn't entirely convinced he was lactose intolerant b/c DS is typically a happy baby even when spitting up. So i decided to try gentlease instead. It seemed to be OK for around 4 days , but now the past 2 days hes back to spitting up, still is gassyAND still has his cold so hes coughing and sneezing, and I just took his temp and it was 99.9 and he just had diahrea. So now i am wondering if its that hes sick or is it really a milk allergy. Should i call my ped or wait till the AM? They dont consider 99.9 a "real" temp so i'm afraid they are going to blow me off tonight and just say bring him in tomorrow. Please any advice would be great

Re: Help please-How do i know if its a milk allergy

Well, I'd just bring him to the ped. and ask them to do a quick test of a dirty diaper and that'll tell you if it's a milk allergy. Also, a milk allergy is an allergy to the proteins in milk, lactose intolerance is the inability to digest the sugar in milk (lactose). So they are two different things.
It could just be a stomach bug, they are going around. But if you feel there's a need to test him, definitely do so. All you need is a dirty diaper and the doctor.