My Elbow is Soft

For some reason, my left elbow is full of liquid. The skin is bulging out into a sort of knob, and it's very soft to the touch. This is odd. I've never had my body do this before.

The right elbow is okay. I checked it as soon as I felt my left elbow and thought hmm, elbows aren't supposed to feel like that, are they? I thought it might go away overnight--be reasorbed into the body as long as I didn't stress it, or something--but it didn't. Weird.

Update: I think it's bursitis. Time to see a rheumatologist, I think.

Update 2 (7/22): Good news--the rheumatologist I called had a cancellation, and I can see her tomorrow. (Bad news, they're doing construction upstairs, and talking on the phone is a risky business, since you never know when the buzzsaw's going to start up. I hope this doesn't last long.)

Update 3 (7/31): The bump started shrinking a couple of days ago. It feels partially deflated when you squeeze it. Not that I'd do that.