Birthmark or What?

So, close to a month ago, an oddly-shaped red splotch showed up on Kevin's belly. I thought maybe we'd accidentally pinched him snapping a cloth diaper or something, but I watched the spot, put a little baby lotion on it & after two weeks, called his dr. She said to try putting Aquaphor on it for a few days & come in if it didn't clear up. I did, it didn't, so we went in & saw her. She deemed it something akin to a birthmark. Late-bloomer. It doesn't seem to bother him at all, so I felt relieved.
Then, he got these red lines on his legs that were clearly from the diapers... I later narrowed it down to the overnight diapers we were using.
So, we went to the cloth diaper store and showed them to the lady that owns it & got some new diapers to use overnight. After taking a few days to pre-wash them, we finally tried them. They're ginormous! It's so hard to get the covers over them! They're hemp & he can still soak them through. They're supposed to get more absorbent after more washings, and we can add inserts...
But, at any rate, the marks on his legs do seem to be getting better. The splotch on his belly, however, remains unchanged. *shrug*