How old are you? How long has it been since puberty? If it's not been long.. then it's not really serious. But to me, it sounds quite complicated. Honestly, visit an O&G specialist. Endometriosis might be the cause, might. There's plenty of others to elaborate, so it's best you visit the doc. Doc will probably provide you some hormonal pills to get you through this. Hopefully it works, but almost certainly after your first childbirth it'll go away! Best of luck.
Well said.. you have pointed out right facts in regards to pain killers. Unfortunately, clots formed from GI bleed stays only in the GI - intestine.  It causes blackish stools (malena) or brown vomitus. It doesnt go around the body or travel in your circulation.