I think something is wrong with me

I am on day 48 of my cycle. I have a full feeling and pressure in my lower stomach. I spotted very light pink mixed with clear cm about two weeks ago. I am getting negative pregnancy tests. I am cramping so bad the last two days but today it's almost unbearable. I feel like it's contractions from labor it hurts so bad. I've had an ultrasound About six months ago and there are no cysts. Can someone please tell me if they have an idea what's going on. I am in so much pain and I usually take pain well. Thank you