If you have to pay for your prescriptions it is worth getting a prepayment card.
Your GP might prescribe more medication to take with the gabapentin. I take it with amitriptyline. Sometimes a combination works.
I suffer chronic pain, my body thinks my panc is hurting, panc is dead so no pain but nerve endings have remembered pain plus i do have liver pain. My combo doesnt take pain completely away but it is bettter than not taking anything. I do have some very strong opiates but try not to rely on them (somedays ive just got to take them but all human functionality goes)