Hi My 5 Year Old Son Was Allergic To Milk

Hi my 5 year old son was allergic to milk as a baby, but is on a normal diet now. He suffers with terrible wind and his stomach seems to be swollen and stick out. Should i take him to the docs?
Also he seems to be drinking a lot more and also urinating a lot. He's got an increased apperite as well. Should i seek medical advice