I need some help here. my 3 month old son has got a redish ring to his skin in places. I think it's…

I need some help here. my 3 month old son has got a redish ring to his skin in places. I think it's a reaction to the lotion I put on him yesterday. it's not bumpy Or raised. doesn't even seem to be bothering him at all. he's normal. ots a little warm to the touch but barely. what is it and should i worry???????