What Causes Swelling And Itching Of The Penis?

hi there please help. i've been with my partner for 3years and we have unprotected sex alot of the time.
However the 2days ago we had sex my penis became swollen just under the head and nowhas become swollen on the bottom of the head. it doesnt hurt but my testicles are seeming to itch more often.

After sex she is in some sort of pain but only after she cums.

is this normal?