Does not look like acne

I'm starting to think he's allergic to the formula. He's on Similac ProSensitive, he's spitting up alot, has alot of gas, and lately he isn't pooping like he used too, then he's left straining and crying, while trying to go. He started off with baby acne but now it looks sort of like eczema. Two of my other children had this reaction and I was told by their pediatrician that it was brought on by an allergy to lactose. This time around, a new ped and she's saying it's acne and will clear up, granted she say it when there was only red bumps, not this. I'm thinking of changing his formula... any suggestions?

I'm hoping it's not itchy or anything because they sometimes get really irritated looking and then it's not so bad... this is a not so bad time, it's usually red and kinda inflamed looking.