Gza1

hi im 20 and ive been training 2years, and ive always trained properly never done any behind kneck movments, and never had any problems at all. untill about a month ago i was training chest and i was on the hammer chest press doin my wrking sets which i can normally knock out a nice 8 reps, but my friend help me lift the left side no problem, he then helpd me lift the right which is what we always do save injury, but as i lifted my right side i hada sharp pain in my front delt, i tried pressing i did bout 2 reps and it really didnt feel good at all, so i got my stuff and went home. the next 2 days was hell my arm was killing, and since then it hurts i havent trained chest properly since, i have no idea what it could be, its very frustrating because i can train shoulders no problem and i can go quite heavy, and also back, pull downs are fine, but close grip pull downs with handles hurt alot. ive read a lot ov posts but i still really dnt knw what it is, its been over a month, i dont really knw much a bout rotator cuff and the symptoms, my friend said it could be a ligament. but im really nt sure any help would be great thanks