Hello there I'm a 17 year old left arm seamer, I've got a problem with my action which is causing me pain in the lower back and was wondering what are people's thoughts and idea's on how to improve/alter my action to help relieving stress and possibly help getting quicker in the process, if possible.

Here is an image of two pictures showing my bowling action from in front and behind:


Two years ago I injured my lower back bowling in a game and stopped playing for a bit to give it a rest but then for the rest of the year I couldn't bowl on it without feeling it "pull" . In the off season I went to a specialist and they said that it could have possibly been a stress fracture, which after a few x-rays turned out it was (only?) torn muscles across my back. I had physiotherapy for it and it felt okay when the season came around but when we started playing games it just kept coming back. This resulted in me wearing a back support for the entire season as a precaution and for it allowing me to continue to play with less worry.
It now seems as if I feel I can't bowl without the support two years on, as I'm worried that I might get injured again if I don't wear it. With it on, I feel minimal pain if any but if I don't then sometimes I feel that pull of the back muscles again. Is it all in my head or do you think it could still be helping?
Are there any thoughts on what I need to do/how to improve my action to aid me in the future?
Many thanks.