Whats my correct diagnosis

For the past two days I started feeling abdominal pain or the lower left side on the belt line.The pain I could feel it when I press on the spot or I stretch backwards.I went to the doctor he first suspected kidney stone but after urine test another doctor said it was a genital ulcer. This was after he asked about my sexual life to which I told him I last had unprotected sex with a partner whom we had tested HIV negative 3 months ago.The doctor then gave me an injection and some tablets for genital ulcer.Up to now there is no discharge or problems on passing stool. The pain is now deep inside like minor cramps, cutting and gnawing but not too painful.I want to know what could be my correct diagnosis, is it a serious condition or a minor one.Is it an STI or not.Should I continue taking all the medicine or not.Now I feel slight constipation or fullness of the stomach and slight heartburn and a feint headache. I suspect this could be the result of the medicine.