I'm someone who has gone through this and still sometimes suffer from the muscle spasms 4 years on.
My prolapsed disc was in my neck (C6/7) with severe muscle spasms and affected nerves. I ended up with dehydrated discs and some degeneration of the surrounding bone.
With regards to muscle spasms, The best thing I have found is to keep relatively fit - yoga, Pilates and general cardio have all helped keep it at bay. When I was first diagnosed, I was off work intermittently for 6 months, doped up on a variety of diazepam, amytriptiline, pregabalin, naproxen and co-codamol. The best management I have found is noticing when it starts to become severe - arm numbness, loss of strength - get myself to the doctor for the meds and refer to physio for exercises. Trying to work through it and carry on as normal just drew out the process. Once I understood what was about to happen and immediately minimise activity, the spasms would disappear after only a week or so.
Like MyVision mines been ongoing for years. As its in the neck, doctors are generally reluctant to do anything invasive so you're usually told to put up. I have never been allowed nerve injections though. And similarly, I was told by an osteopath that keeping my weight at a healthy point and doing general fitness would reduce any possible flare ups. I still get stiffness and limited neck movement but probably have a flare up now around once a year.
It's hard and frustrating to live with. It's the small things - I always wear a scarf in winter to keep it warm, I don't do activity that involves bearing my weight on just arms, I sleep with 2 pillows in one cushion, and I always have spare diazepam just in case.