i have an infected bursar on my left knee and it's quite painful. i stand up a lot for my work and the swelling has gone down into my left ankle and foot.
Actually I had an infected bursa in my elbow in which the infection came from an impact. The bursa gets irritated and enflames itself. I was out of training for a month before I was even able to start thinking about it.
The swelling may go down in as little as two weeks, but it's easy to aggravate until it's completely healed. That could take some time.
the bursae became inflamed from repeated trauma from shooting, etc.
i was given a course of antibiotics to reduce the infection as there was something in my leg symptomatic to infection. the doc asked if i had any recent cuts, bites or rubbed up against any fauna and i couldn't recall any.
either way there was some infection and the swelling has come down. my knee still hurts like hell and i guess it will be another few more days till i can train again.
i've since spoken to other people who have had this problem and it takes a while to recover fully and may occur again.
Not all bursitis becomes infected, but bursitis caused from impact is more likely to become infected (thus the relationship between impact and infection--"came from" may not be semantically correct but is contextually clear).
I recently had an single impact-caused, non-infected bout of bursitis. It took about 3 weeks before I could do any type of cardio in the gym. The first thing I was able to do without pain was the elliptical, and within a week could do as much as I wanted on that particular machine. At 5 weeks I could begin to do workouts on a Stairmaster. At the 7 week mark I was comfortable hiking and climbing literally all day on it, and now at 9 weeks I am back to gradually extending lengths and elevation gains on runs.
My doctor noted that as this was non-infected and came from a single blow, the chances of recurring bouts of bursitis were smaller for me than for someone who had bursitis brought on by over-use injuries or stresses.