I went to my physio session with my ridiculously swollen knee. My PT got a second opinion from a senior PT who in turn sought another opinion from his superior! None had any firm idea about why my knee behaved like it did
Normally, swelling like this is an indication that you are doing too much for your knee at its stage of healing. Try backing off and doing just your daily activities for a couple of weeks. That should allow some of the swelling to come down and allow the inflammation to lessen, which causes the swelling.
my knee seems to be getting better at quite a good rate - phew
This is really good news. Now, to get that swelling down!