I Have Two Knee Replacements And The Last One Was

I have two knee replacements and the last one was done 6 weeks ago. I have lots of pain and stiffness in the 6 week replaced knee and that is expected but my other knee is a bit swelled and stiff. I have been riding a stationary bike is that good or bad. Actually the 6 week knee is very stiff and gets swelled a lot I use ice and heat. Can weather cause this or am I doing to much on the bike?