I Have Been On Tofranil For 33 Yrs. The Doctor

I have been on Tofranil for 33 yrs. The doctor recently took me off that med because it was old and not good for my heart. He did take me off it cold turkey. My mental health practioner is trying me on zoloft. I am having a hard time getting to sleep and staying asleep at night. She gave me Gabapentin, but that really doesn't help much. Any suggestions?