pins and needles post new physio exercise

Hi everyone, First time poster here and new to it all. Dislocated my knee on the 28th Feb this year and have been in an immobilser and crutches ever since, going for an MRI on the 30th April to see whats going on inside knee etc. Still really swollen saw surgeon last week she ordered MRI. My question is have been doing physio and just yesterday go the exercise where you try to bend you knee and then straighten it and push it down straight. (hope you knwo what I mean) Anyway when I do this exercise I get pins and needles in my left foot around my toes and across top of my foot. It has been there since 1020am this morning when I did the first lot of them. My knee is incredibly stiff and it takes all my strentgh to just bend it where I can get it to now. I am ment to do this exercise 5-6 times a day. My physio is now on holidays and has left me to do this exercise until he comes back but I am just unsure of if this is "normal" or not. Can someone please shed some light on this for me. Any ideas would be greatly appreicated. I also have to wear a compression stocking to help reduce the swelling so I took the brace off and the stocking and pins and needles are still there. Thank you so much in advance for any ideas. Smiley