"What the heck does an appendix problem feel like?" It feels like a punch to the stomach - except with a sledge hammer - this is why people with appendix inflammation double up in pain, sweat and even cry like babies. http://www.healthline.com/adamcontent/appendicitis?utm_medium=ask&utm_source=smart&utm_campaign=article_toc&utm_term=Appendicitis+symptoms&ask_return=Appendicitis#symptoms for more on the location and how the pain worsens. Appendix related pain is usually in one location: http://www.fotosearch.com/LIF145/ped06001/ gives an image of where McBurney's point is. If you suspect the testes are involved you are definitely rule out appendix related issues. However this opens the doors to other more interesting ills which frankly you should see a doctor about. Since pain is only one symptom here - and how that pain is and what your gut feels like with thumping and jabbing (which a doctor will do) its a very hard call to diagnoses what could be wrong. The list is relatively long on the possibilities - some include (by by no means are limited to): 1. Abdominal Muscle strain/pull/rip/tear. 2. Bladder/Kidney/Urinary tract infection. 3. Prostate issue. 4. Stomach flu (although it mayn't affect the testes - it could be painful enough to make you think appendix). 5. Gall bladder issue/stones. There are others.