3mo son’s nipple bleeding?

I wanna say first that I already called the pediatrician and they said it’s probably a late reaction from the withdrawal of my hormones from birth and to just keep an eye on it, but I wanted to see if I could find if anyone else has any experience with this too. I’m a first time mom so stuff like this freaks me out a little extra.

So yesterday I noticed a small dot of what looked like blood on my son’s shirt right where his right nipple is. I lifted his shirt and didn’t see any sign of trauma, no redness, scratches, nothing. So I figured it came from me because I have a small cut on my ear that I was messing with and just changed his shirt and left it at that. Then today this evening, we were doing tummy time and when I lifted him up, I noticed the dot was back. I lifted his shirt again and saw nothing. I pressed lightly on his nipple and a small dot of blood came out of the middle of it!! He didn’t seem to be in pain and there were no lumps but that’s when I called his doctor and they said it’s fine. He’s acting just like he normally does, I’ve just never heard of something like this happening before.