Treatment for cording - at home

Hello all!

New here (well, newish, 10 years after the first time...). I've had lumpectomy and removal of 2 lymph nodes - lucky that my breast cancer, just like the first time in the other breast 10 years ago, is not the worst brand, and hoping to not need chemo, to get away with just surgery, radio therapy and hormone therapy.
However, just 3 1/2 weeks since surgery, I have developed cording under my arm (armpit and nearly to elbow) and in my breast tissue (armpit to nipple, down the side). It is sensitive rather than painful, and I have relatively good arm movement, but I am keen to treat it to get rid of it.
My post op physio appointment is not for another two weeks, so keen to find info and resources of how best to deal with this right away - i.e. what kind of massage, and what kind of exercise.
The internet is chock full of contradictory advice (light pressure massage, deeper massage, different types of exercises). I do the exercises in the booklet I got in hospital religiously, but that is not focused on cording.
Anyone here has good advice to share, and quality resources they can point me to?
Many thanks in advance, and I wish you all the very best wherever you are in your cancer journey.
All the best
Catherine