i noticed this bump on my foreskin after a heavy weekend of sexual activity - Ive been to doctors who said its nothing to worry about, any ideas what it is? 
Doctor is probably right - you most likely have something like a blocked pore or inflamed gland and it will take care of itself. What you need to realise is that during sex there a great deal of friction going on, particularly on the foreskin … so we are quite fortunate not to get a whole lot of this thing going on following prolonged sex or masturbation ..
As ever, keep a close watch for anything else going on - should disappear in its own time …
thanks mate, i was just a bit confused. Its not herpes or warts, but im always weary or any bumps/lumps down there!