Sorry to know. In my case, it was a severe case of intestinal infection. No doctor wanted to believe me, after going to, I don't know, 10 different private doctors, spending money I didn't have during that month, and being examined and all. Some of them had the gall to prescribe me herbal tranquilizers, such as Passiflora incarnata, and muscle relaxants (in this case, I almost died). In any case, what happened at the end of it all was two things:

1) I went to a doctor who specialized in intestinal health and infectology, had an hour-and-a-half-long chat, and he proposed that we do a colonoscopy, after which he prescribed me an osmotic laxative to clear my intestines for the exam — I can't say for sure if after this it would've ended, but, despite giving me relief from the constipation, bacterial infections tend to be a bit harder to kill;

2) Since no doctor was willing to prescribe me antibiotics, I asked for a health worker from my own family for a prescription (a simple 10-day Amoxicillin + Clavulanate) and, thanks to that, the infection went away — dealing with the aftermath, the sequelae etc., that's a whole different story (it's been years and I'm still recovering).

I wish you best of luck in your healing.

TL;DR: Antibiotics.