<s>[INST] I have a sharp pain in my penis from the bottom of the head about half way down the shaft. It only happens when I get an erection. I drink a lot of cranberry juice and water and I have had one partner who I know has been faithful for almost 2 years. What could this be? I am 22, and am uncircumsized. [/INST] Hello, It may be due to several causes, still may be due to referral pain due to renal or bladder stone. So for further assessment I would suggest you to consult with urologist. He may procure urinalysis, ultrasound abdomen as per evaluation. Further treatment mainly depends upon the underlying condition. Till then for pain you can take tablet acetaminophen. Take care. Hope I have answered your question. Let me know if I can assist you further.  </s>