JoJo, you might try sleeping with the affected arm on a soft pillow which raises it up, not so high it's uncomfortable. I do that for lymphedema in my left arm and it really helps.
Love, Lolly

It is also very important to keep the fluid moving and not to let it pool. We need to get rid of those toxins. I stay away from the primary site of the cancer when I do my own massage that is how I was trained to do it. The best way is to do it in the shower as the gravity of the water running down the arm works very well for drainage. Good luck. Hugs, Sandy H.