Thanks for your query.
Pain in foot and knees is likely to be due to muscle spasm in the area.This might be the cause of stiffness
in this region.
You need to do muscle strengthening and stretching exercises around ankle and lower leg to strengthen the muscle and to relive the spasm.
Doing hot fomentation and applying muscle relaxant
gel will be helpful.You can take anti-inflammatory drug like motrin
as and when required to reduce pain.
If the pain and spasm is persistant even after these measures, then I suggest you to get it evaluated by an orthopaedician for examination. He may advise you for the xray to see any bony changes.
I do hope that you have found something helpful and I will be glad to answer any further query.