Hi @Hillbilly
I did not have Herceptin but I did have chemo and radio. I had very painful knees for a while (could not kneel down) and think this was a lasting side effect from chemo. It did go after a few months. I think the pool walking and exercise will definitely help. I did lots of swimming and walking (still do). I think moving helps to strengthen the muscles and support your joints. Hope that your pain improves soon. Chemo effects like this just seem to linger for a while unfortunately but in my experience they do improve. :)