Anyone on Kadcyla after chemo and having side effects?

[Texaskat]

After 6 rounds of chemo I was on the Herceptin and Projeta cocktail for 4 cycles when my doc suggested we switch to Kadcyla which was showing better long term results for killing any cells with my type of breast cancer. I've completed my 9th cycle but am just experiencing side effects I wasn't expecting and doc keeps saying it's the residual chemo (my last chemo was Nov 2, 2021). My hair growth seems to be stunted, it's just frizzy and broken but not growing. My fingernails are constantly splitting past the wick and peeling. I have bad headaches and some days migraines. Since chemo I've gained 15lbs and cannot get any of it off. Last treatment I had terrible water retention and swelling in my left leg, it was 2" bigger then my right leg, and a ping pong ball size of water on my knee for 5-6 days. My joints are on fire most days, especially my elbows and hips and wrists and my hands get really achy and fat. Doc keeps telling me these are not the side effects of the medication but it is the only thing I'm on so what else could it be?