I ride platforms and had similar pain that I think began when I tried to keep my foot a bit straighter on the pedal (it naturally tended to tow out). A professional fitter raised my saddle a bit and I started to just let the foot toe out as it wished. It ultimately solved the problem, but I only took two easy rides over five weeks and didn't press at all for another month before the knee really started to feel stronger. (It was probably another month before it stopped twinging if I accelerated hard or otherwise put too much extra pressure on it.)

You need to address the cause, but you also need recovery time for the injury.

(edit - but yeah, always good to see a doctor)