Claire, so sorry to hear about your setback. The same thing has happened to me. Last Sunday I took our dog out twice. Walked down to Church in the afternoon for a very special service to license our new Vicar, stood for a long time, then walked round to a reception at our local school. Knees were fine. On Monday we danced for 2 hours at Cheltenham Town Hall. Tuesday I walked down to town twice and had my hair done, then went to our dance class in the evening. Since Wednesday I seem to have gone backwards. Under my knees has been burning and pain has travelled part of the way down shins. Also muscles down outside of left leg are tight and get very painful.
I suppose it is a case of peaks and troughs and learn by your mistakes. In future I shall have an easy day before dancing, and not do too much two days together. I have felt depressed all day as last Sunday I really felt like I was progressing in a steady upwards direction, today my knee is 6 months old and painful but more depressing is the fact that the one which is 14 months old is more painful still, having been pain free before. I think I have gait problems and am putting a lot of pressure on it when it is still quite weak. Also I lost so much weight with the UTI that my arm and leg muscles seemed to waste away. Hopefully we can both look forward to the day when we shall be able to forget about our knees and get on with life. We certainly seem to be on a roller coaster at the moment, and I shall be glad when the ride ends.