I Have To Have A Mood Stabilizer For My Bipolar

I have to have a mood stabilizer for my Bipolar 1 condition. The lithium was eating up my kidneys. So I take Trileptal. My primary care physician prescribed Gabapentin, mainly for pain, I guess. I am very concerned about all the side effects of these 2 meds being combined.. The primary care physician knows about all my psyche meds. I just realized this while in the process of refilling the Gabapentin.
Thank you.