Dull ache in base on penis when erect

Hi,
For the last week I have had a dull ache and niggling pain at the base of my penis.
I feel it when I cough and when I have an erection it’s quite painful if I push down on it (even walking or moving it when I have an erection hurts).
It’s on the top part where the base joins the body.
I don’t think I had a trauma (I am sure I would remember) but its been since I had sex on Sunday.
The sex wasn’t aggressive or anything but I did notice that my erection seemed a lot thicker, bigger and really hard, more so at the bottom.
I can’t seen any marks or feel any bumps etc.
I am taking anti inflammatory and I am resting as much as I can.
Any ideas on what this could be?