<s>[INST] whilst having sex there was a popping in my penis, when i looked at it there looked to be a blood vessel spilt, this was on my shaft of my penis. there was also a burning sensation and there was a pain travelling to my helmet. What could this be? thanks [/INST] Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. In my opinion you had fractured your penile shaft, these are the classic symptoms of penile fracture which includes pop sound followed by bruise over penile shaft with loss of erection and burning sensation. I would recommend you to seek medical attention as soon as possible because penile fracture is a surgical emergency as it may lead to erectile dysfunction and permanent deformity in the penis. Hope I have answered your query. Let me know if I can assist you further. </s>