TKR on left, pain now on left side of knee in lateral ligament area

I had a TKR of my left knee in July and it was great until about a month ago. The outside of my knee now hurts. I take Eliquis so the tylenol doesn't do anything for the pain. When I'm sitting there is less pain, but when I get up to start walking, I wait a second or 2 to make sure everything is alright and then take steps full of pain. It takes about 6-10 steps before the pain starts to subside and as I walk more it gets less, but it is always there. From looking anatomy figures it seems to be the lateral patellofemoral ligament. When I am sitting it is stretched and when I'm walking it is shortened. Does this make sense? Has anybody experienced the same thing?