I agree with Annieko. I would ask the pharmacist. They are often more knowledgeable than doctors as to what meds work better. Good luck

Yes. I was put on pregabilian first and changed to the gabapentin for that reason

Lyrica is gabapentins big sister.
It's just a stronger form.
I've heard it causes tiredness. Maybe you need to give it a little longer.
If you still feel awful you need to call your doctor. Maybe stay on gabapentin if it's working. I've tried other things n had to stay on gabapentin my self

Sorry I have not been on either medication.

Did you go straight onto 600mg a day or were you built up to that? When I first started pregabalin I took 200mg on my 1st night (was supposed to take 75mg and then build myself up) woke up very late for work and walked straight into my bedroom wall as you can guess I was off my face! I take 300mg a day so that I still can take more if I have a flare but then I still feel dizzy and sick if I take an extra tablet. 600mg is the maximum dose maybe it's too strong for you, as your description of how you feel is how I do when I take an extra tablet. Hope it all gets sorted for you soon