What causes burning feeling in left testicle and penis shaft?

Testicle Pain. Testicle discomfort usually comes from inflammation, not infection. Antibiotics are useful, but alone don't always help. I suspect you have prostatitis as the cause. Prostatitis can refer pain to the testicles, penis, groin and more. Increase water intake, reduce caffeine, begin nsaids (aleve) with food twice a day for two weeks. Hot soaks in a tub helps. F/u with md if not better in 7-10 days.