Hi @pookie Cording is creepy and it's not given the attention it should be in pre-op discussions; most of us find out about it the hard way.
I've had problems with it on two occasions. 12 years ago the approach was to use gentle stretches and moderate massage. That did nothing for me and, eventually, my physio reluctantly agreed to do what is called friction massage with the idea of 'popping' the cords. We both cried during that, but it seemed to do the trick. In 2017 I had a different physio who took to cord popping with all the enthusiasm of a kid snapping bubble wrap. I still cried but the results were not so satisfactory. There's been a great deal of burrowing around happening in one armpit so perhaps the scar tissue is causing the ongoing problems.
None of that helps you today though, does it.
The most effective stretch that I've found is called 'childs pose' if you aren't a yoga person, Google it. Down dog is good if the cording moves into your forearm.
There are a series of stretches which some physios recommend which include one where you walk your hands up a wall (Google walking hands up wall axilla stretch) but I find the yoga moves better as you can use your body weight to help deepen the stretch. That, of course, depends on your general physical condition. The hand walking one is quite safe and can even be done sitting in a chair if necessary.
Try both and see what suits you best but please take it easy to start with until you get used to the sensation and you figure out what your range of movement is. Be warned, it feels horrible. Massage as much as you are comfortable with as well.
Try to get a physio appointment when everyone comes back to work. Mxx