Hi Chandra4intx,
It is great to hear that you are doing so well after transplant!
I would strongly discourage anyone from jumping on concrete! It is the fastest way to injury, unless you are under 10 and still have rubber bones
This may not be arthritis but may be an overuse injury. Alternatively, it is possible that your knee pain is because of patella tracking issues, especially since you are still having tightness issues with your muscles/tendons. I have this problem now because of muscle atrophy.
Use ice to bring down the inflammation and try the Cho-pat strap under one of your knees. If this makes it feel better, it is likely a tracking problem and PT is in your future
Good luck - you will get through this too!