Severe pain

Experiencing severe pelvic pain for 3 weeks now. It started as shooting pain up my vagina and uterus to the point i couldnt stand. It has gotten almost unbearable the last 2 days and my period is 5 days late but I'm getting negative pregnancy tests. I have an appt tomorrow but I'm not sure I can wait. I did my first round of clomid in January but my Dr said it wouldn't be from that. Anyone else ever experience anything like this? Feeling miserable and worried!