E.B.
Hi J.,
It sounds like he could be reacting to something in the formula if it is not a virus. You might want to try a different one and see if it works. it could be a milk allergy. I think it is unlikely that he is lactose intolerant in 2.5 months, since breastmilk is very rich in lactose, although it does happen. it is more likely that he is reacting to milk protein or to something else in the formula.
I don't think soy formula is good for babies, most especially for boys, due to its estrogenic properties and its effect on the thyroid, but you might try a formula that has the milk protein already broken down.
Good luck!
E. Bender, NC, CHN
www.nutritionforthewholefamily.com