Pain since years. Please help me. i beg!

The inside of my vagina hurts and burns.Its a weird pain like some one has rubbed green chilis inside. I have not have sex in a year still it happens . I have seen 12 gynaecologist and 2 urologists. Taken a million medicines no relief. The pain is constant stars anytime if I'm at work or anywhere. I drink 2 liters of water everyday.i have taken 6 urine cultures and 3 routine it's sterile. 3 times I've got an ultrasound. It's all fine. I've inserted pills in my vagina had medicines to eat had alkalinezers etc etc but it repeats. Every time I go to the doc I get new medicines without understanding the cause. I don't have sex because if I have sex after one day I have to sit in the washroom for 6-7 hours the pain is weird that I can't get up from the pot. I pee normally then in drops but this is only after sex but now I havnt done it since one year .taken antibiotics still the same problem . The doctors have checked from inside too but nothing it's fine .please help me . I beg