What you experienced is a wet dream while awake. Most of the time wet dreams happen while the guy is asleep. The body makes semen and sperm no matter whether you masturbate or have sex. And when your body get completely full of semen, it is going to come out.

I suspect the pain is coming from not having any ejaculations to dripping cum for a while and then masturbating and then trying to masturbate again.

I know that some cultures and religion have taboos on masturbation and sex without being married. The truth is a male reproduction system is more healthy is there is regular ejaculation either from wet dreams, masturbation or sex.

Some guys will have these wet dreams more often and that takes care of the problem. Some like you, the body waits until it is "busting" before the wet dram happens. That is much like the bladder, if you just refuse to go the restroom long enough, eventually the bladder will reach full capacity and you will start leaking or gushing urine on yourself.

If the soreness continues, you need to see a doctor.

BTW a study was done some time back that showed that men who masturbated regularly like every day or had sex everyday when they were in their twenties were much less likely to have prostate cancer or prostate problems later in life.

If you want to "save yourself" for marriage, fine. In the meantime, do your body a favor and jack off once or twice a week.