It is ok. Be relaxed and within a few days you will be good. You simply made a big effort with your muscle and sperm has left in you.
Hi Stop holding yourself just relax when Climax then you will not feel pain ,
At your age not getting Erect could be Anxiety , Please relax your penis hasn't gone smaller at all , Please Enjoy your Teens ,
Stop masturbation for some time. If and when there is sex arousal, do abdominal breathing to calm your arousal. Google abdominal breathing. Learn it and do it when you want to calm down your arousal. Some restrain on masturbation is necessary.Do not see porno. Involve your self in games and other activities.