Here is a webinar on scars, cording (usually in the armpit) & swelling, post op - and some exercises to help recover range of movement from cording.
I haven't watched all of it - but it looks good.
https://counterpart.org.au/information/past-webinars/scars-cording-swelling-recovery-after-breast-cancer-surgery/Lots of other webinars here to check out too :smile:
https://counterpart.org.au/information/past-webinars/