Hi and welcome.
Glad to see you have joined the forum. There is something called restless leg syndrome, their is a client on the forum called Gollymac and he suffers with restless leg syndrome, he may be able to help. It may also be worth returning to your GP for further investigation. It could be to do with your nerves in the back being trapped, but it could be Neuropathy, but this usually starts in the feet.
I also have problems with my back and have had my Facet joints injected recently, but i am still getting pain but not sure if thats due to being cold.
I am atype 1 diabetic on insulin four times a day and metformin, and the some of the same tablets as yourself.
Have a good look a round the forum as you will find a lot of info.
What type of diabetes do you have.
Keep in touch if you wish.
Good luck and take care.
Tracey