It may be a cyst. The pain meds have nothing to do with the lump,by the way.
Hard to tell what it is if I can't see it,though. I'm not a Dr.,just pretty good in
the medical field. It could be a number of things causing the forearm pain,
that in fact may not have anything to do with the lump itself. Sorry I couldn't
help more.
ii would have it checked by a hand specialist. the lump perhaps is not on your vein, but rather on muscle--it may be a trigger point and this is why it aches. you may benefit from trigger point release and stretching. do some research on tennis elbow or golf elbow and see if the symptoms fit. also research carpal tunnel. hope this helps