you should not have sharp pain anywhere when doing any exercise if you do, immediately stop it and find what's wrong

i am not sure about your sharp pain but i do get DOMS near armpit area when doing weighted dips and bench

looking at the part highlighted in your picture, i dont think it has got to do with shoulder, i think its more like biceps, could be some nerve gets strained all the way from forearm to biceps

mind telling us whats your grip for benchpress ?

i have no exact idea but i think you pulled your tendon or something

make sure when you're benching the barbell should not be at the middle of your palm, if problem still exist i dont know

try to read this

and see if you did anything wrong

http://stronglifts.com/how-to-bench-press-...ulder-injuries/