I have axillary web syndrome (aka axillary cording) even after 2 1/2 years. I just finally found a therapist who deals with it. My last oncologist said to me, "What's that?" So I'm switching again.
For me it started after radiation. My lymphatic system on the bad side was cooked - bottom of ribs to elbow.
There are lots of exercises on the web. I've been doing them, and they do help. They just weren't enough. I'm hoping the vigorous squashing and manual stretching by the therapist will break them up.
It works for some people.