I took gabapentin for a while and noticed that when taken daily--I would build up tolerance (was using it to help me sleep but it became less effective over time--increasing the dose may have helped but I don't like taking a drug that requires more and more to be effective). I have taken myself off everything I was using for anxiety/to help me sleep (xanax, diphenhydramine, gabapentin--due to the fact that they are addictive, I used to switch them around --never taking anything 2 days in a row--going without a couple days a week, etc). For a while (last year), I took the gabapentin every night (300 mg). It made me less anxious for 24 hours straight and helped me sleep but it also made my thinking foggier, I would be drowsier in the morning with a slight headache, it increased my appetite, etc. Then, as I built up tolerance, it became less effective. So I stopped. For about 3 days, my anxiety went through the roof and I slept 1 - 3 hours a night then I went back to my "baseline". I hope to never take xanax, diphenhydramine, gabapentin again--but if I do--it will only be for a short term emergency. Though I do understand that some people can't get by without something. And if it is helping with pain then it may be good to take while your neck is healing. I think lyrica is similiar to gabapentin (ask a doctor). A coworker of mine had a painful back issue after being in a car accident and said it "saved her life" (helped her function by the eleviating pain while she recovered) but caused her to gain weight.
Do you have a therapist? Make sure you understand what caused your anxiety in the first place (if you can--it takes time).