i just came off a serious knee injury and havent been able to lift for 3 months now and suffered muscular atrophy going from 180 to 160. about a month ago i got to the point where i could do some weight lifting so i started light. but now every time i bench i feel like im straining my left shoulder a lot and its got to the point that i had to skip last weeks chest and shoulder workout. i have always felt i had strong form, and i stretch and warm up before every lift. i have been working on my shoulders as much as my chest and i have only slightly went up in weight on bench so i have no idea where the problem lies. anyone else have similar problems?