Dear user, Thanks for writing to Healthcaremagic. I understand your concern about pain in right side back and night emission of semen (night fall as you said). Sexual activity (intercourse or masturbation) in certain positions may cause back pain or discomfort. It may last for hours to days. This occurs due to musculoskeletal reasons. You may consult surgeon for check up to rule out other causes for these. Over h counter pain killers, warm compress, topical pain relievers usually helps. Night emissions or ‘wet dreams’ are normal events. Semen is being manufactured by genital organs continuously but, it has to be expelled by some means. This situation is just similar to a glass of full milk to which you add more milk, with the logical result that it overflows. Similar happens to semen in body. If one neither has sex nor masturbation for long time, semen gets accumulated in its pouch, so it gets expelled in the form of night emissions, which is normal. Increase frequency of intercourse or masturbation will empty the pouch of semen and night emission will not occur. Semen is just akin to other body fluids like saliva, tears and blood. It is produced continuously and gets utilized. Loss of semen in nightfall, during sex or during masturbation does not have any adverse effects on body. No need to see doctor for this. No medications needed. No need to worry. Relax and go ahead with happy sex life. Wish you good health.