Bumpy rash?


I went to change my baby girls diaper and when I lifted up her onesie I found she had a ton of tiny red bumps all over her stomach and chest. Just that part. She's had the same lotion, detergent, and shampoo body wash since birth. The only thing that's changed is we ran out of her formula and bought the kind closest to what we use at another store two days ago. Could it be from the change in formula? She threw up a lot the first night we gave it to her but not since then. I'm going to give her another bath, use lotion, and switch back to her regular formula tonight. No fever and she doesn't seem to be in pain but she has slept quite a lot today. Now she's super alert though.