Vomiting and Seizures?

Rebecca is a 2 1/2 year old with Lennox Gastaut, (previously had Infantile Spasms). she still has the Jacknife seizures typical of IS. She also now has Drop seizures. Thursday AM I was awakened to her crying in her crib early in the morning and discovered she had puked quite a bit. Cleaned her up and took care of everything. Figured it might be a virus, or something she ate the night before. She did not have another episode of vomiting on Thursday or Friday. Fast forward to this morning (Saturday). Rebecca is playing, and has a full body jacknife seizure. My husband picks her up to comfort her. She becoming more alert after her "spell" and then she vomits a small amount on him. I take her and start to clean her up. Daddy leaves to change his shirt, and get me some paper towels. Then Rebecca starts to vomit even more. She had not had breakfast yet, and had only drank part of her bottle (not even half of an 8oz bottle of milk). I tried to Google the topic, and look it up here on epilepsy.com but didn't have much success. Is this a development we need to be worried about? could this just be a strange bug she caught? The 2nd part is doubtful, since she is getting Chemo for benign optic glioma brain tumors and she is rarely exposed to other children or sources of infection. Any advice would be helpful.