HAVE IT X-RAYED!!! Ok, rant mode off
Seriously though, have it looked at. Soft tissue damage can last a lifetime if you don't treat it properly. Missing one or two weeks of aikido, hell a few months is nothing when compared to a lifetime of pain and immobility. When I had to immoblize mine the doctor gave me a sling that had a strap that went around the body. It held my arm close to my body so I couldn't move it from the shoulder. If you absolutely refuse to get it looked at get one of these at least.
I just keep thinking of one of my training partners who dislocated his thumb in class. He "sucked it up" for a couple weeks then when the muscle at the base of his thumb swelled up like a baseball he decided to have it looked at. He ended up needing surgery because of the tendon damage he did by not having it taken care of immediately. He still (4 years later) doesn't have full range of motion or strength and probably never will. His doctor told him if he'd had it taken care of the day after it happened they would have put it back, immobilzed it for a few days and he'd have been back to normal.
Please don't let this happen to you