Suggest Treatment For Vaginal Discharge And Stomach Pain

Hi, I am 20 years old and for the past 2 years have experienced a constant stomach ache, ususally a dull pain that also spreads to my back but i often get very sharp pains in the area level with my hip bones. I am on the birth control pill and have had dark brown discharge inbetween my periods on and off for about a year now. Recently it has been constant for about 6 weeks. I have been tested for pregnancy and it is negative, i have also been tested for all STDs and STI and am all clear, i have been with my boy friend for 3 years and have tried changing my pill to see if it would make a difference but no luck. I have swollen areas in my groin, i believe to be swollen lymph nodes that have been hard and visible for about 6 months. My boyfriend thought he could feel a lump for the past couple of months during intercourse. Doctors have been very reluctant to help me which is gettin very frustrating! I also get very tired and dizzy alot...any suggestions??