Pelvic Pressure?

So, I had my Mirena iud removed 12/2016 To TTC #1. I'm thinking that I've been having anovulatory cycles since then with very light periods. I've been keeping track of bbt and using OPKs. Currently on what I think is cd8. I had a little spotting that turned into heavier red spotting with few tiny clots (this was my "period"). It stopped for a few days. Then last night I had fairly intense cramping with a little gush of red blood. Then no bleeding or spotting today, not even a drop on the pad I put on before bed.  Today I've been cramping a bit with lots of pressure (mainly on my lower left), especially when I squat or lean forward while sitting. I've been to the ob prior, had an ultrasound/pelvic exam about a month ago. She said that my uterus, ovaries and cervix all look normal. I'm wondering if anyone has had a similar experience? This is an unfamiliar pressure/pain to me.