Thanks for your reaction.
Despite 5 physiotherapy sessions (3 hydrotherapy, 2 regular physio) for 5 weeks, things did not improve. My physiotherapist only taught me Thursday how to massage my knee. Although it is difficult to massage yourself, afterwards I can walk more or less normally for 5-10 minutes. Then the stiffness and pain come again, so that I switch to walking with a stiff leg.
Being able to help myself, even only a little bit, is empowering though.
I have appointments with 2 other surgeons for a 2nd and 3rd opinion, for I am so worried.
One postive note though: the homeopathic anti-inflammation drug, Pyrogenium 30K, helped! My left knee does not feel hot any longer. Just take 3 granules and let them melt under your tongue. Take the whole tube or as much as needed. It is efficient, cheap (at least in Belgium) and has no secondary effects.