Sharp shoulder pain

I havnt been pitching for about 2 years and about a month ago I started up again because I want to play at my college next year. My shoulder feels fine when warming up or throwing at less than 60 or so percent. When I start to throw hard I will get a sharp quick pain in my shoulder. The pain goes away very quickly but returns the next time I try and throw hard. It dosnt feel like muscle soreness but I am not totally sure. I was thinking that it was maybe just from not throwing for awhile but it hasnt gotten any better. Any suggestions or help would be appreciated, thanks.

You need to warm up very slow! Your arm is not use to the velocity. Even when I take a week or two off, my arm hurts the next time I pitch. When I throw 2 days in advance of my game, this allows my arm to get use to throwing again. So basicly warm up very slow and multiple times before you throw at 100%.

Any sharp pain is a bad sign.

Have you been to a doctor? If not, you should.

The root cause of the problem could be a problem with your mechanics (e.g. taking your elbows above and behind your shoulders).

Do you have a video of yourself throwing?