1. See your gyn
2. Most likely not a pregnancy but any time a penis has been in a vagina, pregnancy is possible. Women have even had periods throughout a "normal" pregnancy.
3. It sounds as though your body is still adjusting to the absence of the hormones or, more likely, has returned to its previous normal - erratic periods.
The brownish clumps indicate "old" blood that may have been left over from your last, incomplete period. If your periods are not giving a complete flush of the endometrium, there will often be spotting throughout the month. The hormones were, for years, keeping you regulated but your body, left to its own devices, is not doing this.
Either way, pregnancy or dysmenorrhea, you need a consult with a gyn. The above description is excellent and should give the doctor most of what is necessary but other tests are indicated.
Posted: 30 Sep 20:16