Belly button turning dark brown

[PenguinsRabbits]

Probably nothing but noticed few days ago my belly button has turned dark brown to black.

Doesn't look like blood though could be very old blood. I take baths regularly so water goes in it normally.

Also have brown line going from belly button down but that's always been there I think. Any idea what this will be? Going to try and see if I can remove it later. Online comes up with pregnancy a lot but not pregnant and youngest is 12. Also comes up with fungal and infection but how would you tell 2 apart. Only other thing I have is enlarged adrenal gland so a hormone might be out of balance. No smell, appears dry. Thanks.

Have you got Addison's disease? Brown pigmentation of skin in certain areas is a key symptom...

Thanks, not been tested for that. When I had an enlarged adrenal gland hospital doctor said to tell GP to monitor it but GP said didn't know how so nothing happened. Symptoms don't match Addisons / Cushings that much, well about 50% and don't generally have darker skin apart from odd patch. Am generally quite pale. I probably should get hormones checked though to be sure.

All came out in the bath - was just dead skin with blood on it so think its fine. Belly button looks back to normal now.