Does anyone have experience with knee injuries (treating in others or sustaining one yourself)?

About 6 weeks ago, I twisted my knee while reaching for the monitor in bed. The pain was really bad that night and the next day, but then went away.

4 weeks ago I started exercising/running again, 4 times a week.

2 weeks ago I noticed pain around my knee, sometimes on either side and sometimes on the top or bottom.

A week ago my knee got so swollen I couldn't bend it comfortably. I haven't worked out this week and the swelling is coming down.

I'm fine with going to see someone, but not sure what they could tell me. How do they discern between runners knee/IT band issues and something more serious? Won't the first step be to rest it for a few weeks anyway?