What Causes Pain In Penis During Sexual Intercourse?

I had unprotected sex with my girlfriend Several times . Sometime 2-3 times a day. The last time I had sex with her my Penis hurt during the sexual intercourse despite the pain I didn't stop until I cum. Then I noticed red tiny spots on my penis head it was also itchy . I thought it's a friction so I didn't have sex for 12 days . During this period after taking shower I washed my penis with warm water and salt . The tiny red spots disappeared and also the itching . But last night I had sex again but it was so painful too . I didn't able to continue so I Cum so fast . I don't have other symptoms only pain during sex . So what could it be ? Please advice