Whether you are using a milk or soy based formula (especially milk based) your son's system may not be able to handle it. Talk to his dr. about possible milk allergies and switching to a soy based formula. If you are already using a soy based formula, you may try Alimentum. It is the gentlist formula on the market. It is not really milk or soy based, even though it has both properties in it, but pre-broken down for his stomache. The can says it will help w/colicky uncomfortable babies in 24 hours. However, the 16oz cans are $25 per can...Talk to your Ped. He/She can prescribe the formula and there are companies that can fill that order, bill the insurance, and send it to your door for free. If you are on WIC, they will give you a specific company (North American something) but your Ped. should have some information as to who you can go through...If not, call you're WIC office! They should help you even if you are not enrolled.
Talk to your Ped before you switch, though. It may be gas, but if it is allergies, that needs to be addressed. Also, normal formulas take 3-5 days to make any real difference.
Take care!
M. M.