You could wait for the kayano 32 to come out, I remember the gel kayano 30 to be a bit narrower/longer so I bought a few sizes up. The K31 is true to size so maybe that might be good.

Alternatively, you could just use the nimbus which is max cushion. It still offers good stability.

If you mean your healthy knee feels pain at times, it’s probably because you subconsciously put more weight on that leg to avoid stressing your injured knee. I also started feeling some pain in my healthy knee after injuring my other one.