Sharp pain while ejaculating help

Patient: Hi doctor,so im an 18 year old guy,who have been masturbating for about 5 years mostly daily, last month i decided to stop masturbation,but while masturbating laying on back(i usually do it sitting)i had a sharp pain in my penis while ejaculating.so i masturbated again to see whats the problem but nothing happened.now i once again masturbated in bathtub,there was soap and i had that sharp pain again while ejaculating,so my question is could it be because im not used to laying on my back or because of soap…..? im really sorry to being so specific,but you would be helping me mentally a ton if you can answer ps:ive been having depression over last 2,3 years even more

Doctor: