Cold and cough. What are food to avoid?

My 17 month old kid has been falling sick with cold very often nowadays. Added to it the weather is also rainy and wet most of the days. He is taking medicine prescribed by doctor. But after analysing i see that he is sick on and off the whole August and still has not recovered completely...so i had few questions which i couldn't check with doctor: 1- is it ok for a baby to consume medicine for cold n cough for this long time 2: he sweats a lot on head, his hair is grown too, will this wetness cause cold 3: are we supposed to avoid head bath when babies have cold 4: does going outdoor, in wind causes cold..he often wants to go out of house n we take him to short walks on the house lane 5: should we avoid sleeping under AC or fan during cold 6: does certain food aggravate cold, if so what are food to avoid