How to restore this skin dent on my armpit?

[NadaAsar]

I developed this weird skin dent next to a rash I had for two months. It's a weird set of two lines kinda creating irregular grooves... it's not a stretchmark, it's deeper than my regular surface of skin, like it got scraped or dug out, but I swear there was no cut or injury like that. It seems to have just formed after this rashstayed a bit longer than expected.. I don't know what it is and I'd like to know if it can return to normal without surgery or laser.

I had this weird red rash on the side of my armpits. It's going away slowly by using antibiotic creams.