SERIOUS WEIGHT GAIN

Hi all, has any one elso had this issue since I have been on 1000mg a day Epelizin (yes that purple tabs) due to me diagnosed withTonic Clonic epilepsy. My problem is my weight cause I was original 50kg and now I am 60kg. I dont even weigh anywhere near that weight giving birtg to 3 boys. I cannot fit into any of my clothes an i honestly can't keep on carrying this excess weight cause it just seem to be getting worse & I am
exhausted all the time. my appetite hasn't changed & i Only still drink my 2lt water a day.