knee arthritis -worse-don't know what to do

I am 48, hypermobile and for last 8 years or so have had a lot of problems with my arthritic knee.

I've had meniscus trim/repair. TTT surgery, lots of physio and was rubbing along okish.the surgeon told me I have grade 3/4 arthritis in the knee but he does not want to do a knee replacement as reckons results on hypermobile are not good. It did swell up if over did it, did ache a lot, knee cap would sometimes sublux a bit but I could rest up and it would reset to ok 

until 18th Feb when I walked a bit quicker and something went wrong.

Suddenly started having very very painful issues in the hollow behind knee-random stabbing pains for no apparent reason, swelled up and would not go down and knee cap sliding out more often (painfully)

I had a steroid injection via GP a few weeks ago and thankfully it took some of the swelling down-which cuts the background aching -and he has asked for the Orthopaedic hospital to see me again. Apparently they are still considering if they wish to see me- then there is a wait list.

I am getting worse not better. I now cannot walk or stand for more then 5 minutes without sudden extreme pain to level I cannot weight bear. It seems to happen most when fully straighten knee - I suspect I have meniscus catching in the joint but it is beyond sane levels of pain. It calms when sit with it elevated to dull ache with swelling but I cannot just sit for months. Pain killers do not touch the stabbing pain. 

what should I do?  I cannot afford private consult, NHS looks like being months if they agree to see me. I am using a knee brace physio got me before but knee swells up then if feels like cutting off circulation as goes so tight so cannot use it all the time.  

I am literally afraid to leave my home as when it catches I cannot walk at all . 

I just do not know what I should do. family say go to A&E but the locking releases after a while so don't see how that would work as there would be nothing to see