I have the clicking in my neck and shoulder and last week after PT had it in the back of my leg. It could be from the PT making something act up.

I do have injuries on my whole upper body though so I am thinking you might have something else going on besides RSD like the others said.

It's to bad you can't get more test done on you to find out what is going on.
After 10 years, I am finding out that I have neck injuries and thoracic spine injuries. It's took that long to get other things calmed down enough to get it diagnosed by my PT. I am getting ready to see a Neurosurgeon to have some xrays done to figure out what injuries I am dealing with.

You do need to ask your Dr. if you might have other injuries going on in your knee. It sickens me when these Drs. chalk everything up to RSD. Look at how many of us on here have other things going on such as Fibro, Arthritis, TOS and to many other things to mention.

Sorry you had to miss school today. I hope you do start feeling better soon.
Ada