I know some of the other members here have had injections , so I hope they will have time to share what they know.
You can also do a forum search (link in my siggy) for more info until there are replies.
Unfortunately the nerves are tricky to deal with.
Does PT suggest laying in a yoga type corpse pose, for relaxation and very gentle stretching? Diaphragmatic breathing etc?
https://www.google.com/search?q=Diap...w=1360&bih=670