I did not get my periods for two months but now I can find blood on my underwear!

Well, really this is no biggie.

Basically periods (and pms symptoms) are initiated by a drop in your hormone levels. Sounds like yours haven't dipped as much or as quickly there last couple of months. And hence you skipped a period and now only slight spotting and no pms symptoms.

If it's a one off, then nothing really to worry about. Just wait and see what happens next. If your periods start to become very irregular (by that I mean 2 weeks or 6 weeks, not +/- a few days) or you skip 3 periods, then that would be the time to see a doctor and get your hormone levels checked out.

You don't mention your age. But late teens or early 20's is a time when PCOS (poly cystic ovarian syndrome) often starts. That causes hormone imbalances and irregular or absent periods, and it's pretty common (affecting about 1 in 10 women). But at this point, I wouldn't worry about it Just wait and see if you get back to normal or not.