What are your tips for managing spasms lower back?

Hi
I have had AS for six years I got diagnosed at 62 I was told I am atypical for it to start at that age.
I am 67 and if you read a little about me I am in the uk and not managing well with it and the NHS either.
Spasms are lower back, I use tens machine and a small heatpad. I am not on biologics but that’s another story.
So tips for pain relief and spasms the spasms make me scream I don’t know if this normal or not, I am trying to do breathing exercises it’s not easy.
Thank you.