What Would Cause a Bypass Patient to Gain 22 Lbs in About 2 Mo.?

I had bypass 5 yrs ago and not gained any weight back until now. By bedtime I look like I am 9 mo pregnant. Just had small bowel follow the, ct scans, ect. All ok. However this happened after being on neurotin 300 mg tid. Could this med cause this problem? Please help with any suggestions.

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