Hey NovaFreak,
Thought I'd chime in it's been about a month since you posted, but hopefully I can help. Your symptoms describes a tear to one of your rotator cuff muscles, specifically the supraspinatus. There may also be a possible impingement since you have some pain flexing your shoulder.
If your shoulder is still in pain I'd refrain from any raising activities that would aggravate the problem. Let your shoulder heal for at least 3 weeks then start with light isometric raises with a therex band. Progress to heavier resistance and if pain comes back, immediately stop what you're doing and lower the tension/weight. Corticol steroid injections may alleviate some of the pain, but it won't solve your problem. Also use Ice to alleviate the inflammation/pain. Other than that, rest, and good nutrition should speed up recovery.
Hope that helps!
ImpulsEE