Oy ..sounds familiar. I complained about the same thing a few weeks ago. It happened just before I was going away and I was concerned besides confused. Luckily I had an appointment with my surgeon that day. He said it is fairly typical that once you fix one the other acts up since you are likely more active than before -and that since we're not going to do anything about my 'good' knee for a while, just try to find the balance - that word again !!!
So - now that I am walking more I actually find my 'good' knee gets better the more I walk, my new knee gets stiffer. :rolleyespink: When I use the stationery bike, it's the opposite ! And, I just realized that when I am doing stairs, my new knee has become my good knee... very, very confusing are these bodies of ours !!!
Hang in - you will sort out what works and what doesn't. What I have learned here is that if it hurts , it's too much -and that goes for new knees and "good " knees...