Pregnancy rash?

I was changing clothes in front of the mirror a few minutes ago and noticed this small rash under my breasts. It doesn’t itch or anything, but it’s slightly scale-y/raised.

I don’t have many stretch marks (only on boobs from last baby), so I thought it may be the beginning of stretch marks. But my husband, who has stretch marks, says that isn’t how they start out, plus I’m growing in my lower belly, not upper.

Any idea? I’m hoping it’ll go away on its own. If not, I have a doc appointment in a few days anyway.

*edit- i had PUPPS with my first, so I know it isn’t that.