Knee problem during swim workouts

Hi folk! This problem's actually easing up somewhat but I thought it might be worth getting your input anyway. I've been having a knee problem lately that slowed down both swimming and running. Both are picking back up again, and doing better right now w/ the swimming. But for one thing: some knee pain when pushing off walls and/or kicking--and mostly the first few kicks right after a turn. (Don't know if this is relevant, but I haven't been doing flip turns lately. Kind of lost the art and have decided to hold off on that and work on other skills for now.) As noted, there's been some improvement: needed a pull buoy for most of my swim when the problem was at its worst; now I use it less and I've gone from ridiculously slow to my "normal slow." ("Fast" or even "fast for me" are goals now.) Your thoughts? Thanks!