Hi ! Your doctors have excluded almost all the patholgical reasons for the discomfort you have in your testicle. I would advise you to for a good testicular support kind of undergarment. This will relieve your symptoms when you stand. If you are sexually active, then burning sensation once in ten may be considered to be a chance finding without any pathology.
However, because the pain you have in the testis also radiates to the groin and lower abdome, there could be a small calculi, which might not have shown itself in the present ultrasound/IVP. The ultrasound may be repeated to exclude this factor. Sometimes inflammation of prostate gives rise to similar symptoms, and semen analysis
may not be conclusive. This might have to be done repeatedly. Also go for a prostate specific antigen
test on consultation with your treating doctor.
Your bowel symptoms may not be related to your testicular symptoms. For this, you should avoid eating outside specially if you go for frequent fast foods. Go for high roughage diet with plenty of liquids. Amoebiasis
is a very common problem world wide, and get your stool tested for it. Consult your doctor for the treatment.