I’ve had two similar experiences:
15 years ago partially tore the ACL in my right knee – very swollen, painful etc. 3 days later went to GP, sent to A&E, X-ray, referred to specialist, short wait of a couple of weeks, i think, for MRI. Then another short wait for arthroscopy, cant remember how long but less than a month. After follow up had a month wait for physio (this was classed as urgent), then physio for 6 months.
Currently: sprained left knee in early december, swollen, stiff and sore and not able to bear weight but not as bad as previous one. Self treated doing the RICE thing for a week, then flexing exercises from my previous physio in the second week, then gentle cycle machine, stair exercises from week 3. Think I tweaked it again stepping off a curb over Xmas as it swelled up again. treated as before but have a persistent soreness at the back of knee and around the knee cap so went to GP. Got an x-ray within 1-2 weeks, referred for an MRI with a one month wait (private clinic doing NHS work) and referred to a specialist with a potential 4 month wait. The waiting is frustrating but understandable as the referrals are triaged and I’m low priority – I can walk and cycle just can’t run, play football or snowboard :(. Ultimately I’m just hoping for a more precise diagnosis so I make sure I’m doing the most effective physio.
Sorry to go on a bit but thought it might provide some comparable experience.