HELP! Pain left side/ groin area

January I started getting a sharp pain in my left side (kidney area). The pain started radiating down towards my left groin, sometimes all the way to inner thigh.

March I had my last period. I do have irregular cycles, ranging from 28 to 36 days but I always got one.

Went to the doctor in May. 4 preggo tests, blood work, abdominal ultrasound & pelvic ultrasound later and still no idea what the pain is or why period stopped.

No kidney stones. Not anemic. No PCOS. No ovarian cysts. Nothing wrong with my liver or gall bladder. And no baby.

Has anyone else experienced this? Could it be a hormonal issue? Did I have a miscarriage? Could something else be wrong with my ovaries?

I go back to the doctor today. Any suggestions on what I should ask them to test for or what it could be??