Iv been to my gp about my back several times but they keep saying its muscle damage, think its my spine. what can i do?

Go to a specialist: i am not doubting your GP opinion,because i am not your doctor. but for your own peace of mind,go and see a specialist,like a neurologist,or a spine surgeon,,that could be a neurosurgeon,or a orthopedic surgeon,they will give you the second opinion.

2nd opinion.: Why do you think it is your spine? Unless you have very specific signs and symptoms it is very unlikely that there is anything wrong with your spine and X rays are generally not indicated. I agree with one of the other docs - get a second opinion.