Sir, I Hv Been On Medication For Epilepsy Since Last

Sir, I hv been on medication for epilepsy since last 18 yrs., as per my neurologist's suggestion, aftr I cmpleted the dosage course for 3yrs, wenver I hv tried quittin the medicine and hv experienced seizures. I am taking zen retard 200 since long but, I get wavy sensations smetimes in my arms and legs and I always fee discmfort in my stomach viz indigestion, gas and nausea. Pls suggest if I can continue with the same medicine or I hav to bgin sm other medicins?? Pls guide.
Regards
Sid