It is very important that you discuss with your neurologist the adverse effects that you are experiencing with Keppra, so that s/he can tailor your dose and/or switch you to a different medication, safely.
As a supplement, CBD may be helpful for the prevention of seizures. Since ideally you should be covered around-the-clock, longer acting formulations are desirable. These include oral tinctures, which last approximately 2-4 hours and edibles, which last approximately 6-8 hours. CBD oil may be added to your own foods or beverages and ingested, which will give you similar coverage as could be obtained from purchasing edibles containing CBD.