Swollen Painful Veins on the inside of the foreskin

hi, i am 25 male. and i have noticed that everytime i have an erection my foreskin gets a bit tight and when i pull it back, there are 2 veins underneath on the top side of my penis that become swollen as my penis becomes more erect. then as i proceed to pull the skin futher back, they begin to hurt or burn as the skin stretches. then the pain suddenly goes away when i retract the foreskin. i have never had this problem before. this problem developed after i had sex for 4 days straight. and i have been sexually active for the past 5 years, so why is this problem affecting me now, just because of these 4 days of passion? and what is the cause of this problem? and also how can it be stopped?