I’m sorry this happened, it is scary when you see someone having a seizure. Perhaps your H would go to urgent care, where things would be less expensive?
I do think only a doctor, ideally one that knows your H’s health history can answer the question if the meds could have caused the seizure. I hope he sees a physician soon.
Lastly, is it possible to extract an agreement from him that if he has another seizure he will go to the ER? There can be significant risks with having seizures, such as falling and hitting head or breaking a bone, swallowing tongue/choking, etc. It’s a lot to ask that you manage that on your own. Hugs.