The prostate gland is a delicate body part and should never be subjected to an unprofessional. I understand that you never did that. Your body did it itself. But, a bruised prostate can cause problems. They usually mend themselves unless there is damage. My advice is see a doctor. However, if you are unable or unwilling to see a doctor here are a few things to watch out for:
Any pain or blood would indicate a serious condition. Find a way to get to a doctor ASAP. The prostate, in addition to playing a major role in sex, also stops your ability to urinate during intercourse. This is for the protection of your female partner. Urine put into her reproductive system can cause her infection and a host of other problems. You can do a test of this by standing in front of a mirror when you have a full erection, think "morning wood", and trying to urinate.
You should not be able to urinate until your erection starts to go down. An O.T.C. stool softener might help stop your stool from milking your prostate. Prostate milking is a fast way to collect a sperm sample that your doctor may use to save time.
Just a word about prostate examination. Your doctor may perform a prostate examination on you. This examination is done to detect bumps and hard spots on your prostate. If so, he will insert his finger into your anus, and rub the surface of your prostate. As soon as he starts the examination, you will feel as if you are going to ejaculate. Most doctors are skilled enough to complete the examination quickly so as to avoid causing an ejaculation. However, some men have a "quick trigger" and will ejaculate during this examination and the doctors know this. Unless the doctor, or you are asked, to hold a cup in front of you penis, the doctor is not intending to cause you to ejaculate. If however, you have a cup placed in front of your penis, the doctor intends to make you ejaculate. Don't fight it or become embarrassed. You will not be able to stop it anyway. Just go with it.
The above is for information only. Only your doctor can advise on your health conditions.
I had this when I was young. The prostate is very close to the intestine wall and the bowel movement was acting as a prostate milking procedure. It went away in about a year without treatment.