I've been on testosterone (IM injections) 4+ years and haven't had a period since the first week. Suddenly getting spotting (?) again two days ago. (Honestly part of me isn't even sure it's that and not...bleeding from somewhere else, I guess. But I can't remember very clearly what it was like when I was menstruating.) How concerned should I be? I'm going to call my doctor on Monday but I can't do anything till then and it's kind of freaking me out. I know I've seen people mention this before but I don't remember how it turned out for them.

Yeah, I had that happen at about 3 1/2 years on T...monthly.  Quite unpleasant    Resulted in surgery for me.  Turns out I had a HUGE benign tumor attached to the backside of the uterus.  While relieved to have all of those things removed from my body, I had not really planned on it, and the procedure had to be done abdominally, which was a difficult surgery and recovery.  Light bleeding happens to many people after some years on T and then goes away without incident, but I would probably get it checked out though, as it could be something more serious.