Rash? FTM. Should I get it checked?

I have good skin, but in the bathtub I noticed that i have 2 perfectly circular brown spots in between my boobs. I don't wear a bra,  so I'm not sure what could cause it.The bigger spot has kinda dry skin in the circle. The smaller one is right on my tattoo. The tattoo is old.  Any idea what it is? If i should get it looked at?