Any insight helpful

So my last period and this one have been weird.last one I got was 5 days late and probly should b considered spotting since it was so light,even tho I had some bleeding for 5 days. Had the worse cramps of my life even though I was barely bleeding,so bad I was curled into a ball. Having the same problem,19 days later.severe cramping with little bleeding.havent had any clots.not on birth control and all the hormones from them aren't in my body any more.and I've taken several tests,and according to them,I'm not pregnant.any advice on what I should do or what it could be?