While I have absolutely no ability to diagnose from afar, I can say that almost all shoulder injuries are worse with overhead activity and it sounds like yours would be too. Realize that you've likely caused some inflammation and resting, icing and using an anti-inflammatory will help but even with these measures, it will take 4 to 7 days for the inflammation to settle. If you continue to do activities with your arm above let's say shoulder height during that time, you're not really resting it and are likely to cause more inflammation.
The jist of it is, try not to do any repetitive reaching or lifting above eye level for the next week. If all's well after that, get back tonormal activity ASAP, shoulders are notorious for getting very stiff if you don't move them enough. It's a bit of a juggle, avoid inflamming it, but try to keep it moving.
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