HappyHopper - welcome to the site, sorry to hear about your problems.
The way I hear it, it is a muscular issue due to an imbalance created by weakened core muscles which put stress on the outer edge muscles, causing the spasms when they are overloaded by trying to do both the support of the capsule (which should be done by the core muscles) and their own work. The spasms act to protect the area that the body thinks is in crisis.
Don't know what the surgeon's assistant did, but it seems like when you do get the physio, it should work itself out well. April sounds like a long wait, hopefully you can find a specialist sooner. It sounds like massage is one of the therapies, is that a possibility (just to alleviate some of the issues), or maybe look at a roller or even a tennis ball to roll in the affected area to help in releasing the muscles a bit.
Maybe doing some of the core exercises listed on this site will strengthen the muscles and help tide you over until the physio can get to you.
Good luck, it sounds like it can be dealt with, sorry about the fact that you have to.