Have you seen a doctor? Do you think you have a serious injury, or just muscle fatigue? I've been dealing with a serious shoulder injury for years, and I'm generally able to do most anything, so long as I'm smart about it. Stay away from shoulder locks (also, for me I sometimes have difficulty posting on that arm, as it will occasionally subluxe if I don't do it right. Keep it light, keep it slow, and tap early.
Way back when after I had originally injured it, I decided I would take some time off to let it heal. It ended up being almost 2 years before I returned, and it's still not 100%. In fact, it won't ever be 100% again. If you end up taking more than a couple weeks off, I would strongly suggest you go see a doctor and get it properly diagnosed.
Other than that, ice and ibuprofen are your friends!