jesho
your experience is so scary. I think i will freak out if in your shoes.
My boy had stomach flu not too long ago too. I suspected it when he first had diarrhea and then followed by the loss of appetite. It was quite mild since one day he only had diarrhea once, but i scared of dehydration to i tried to give him more liquids but he was not so keen to eat or drink. I gave him yogurt and probiotics. The next day, he vomited twice (small volume). As it was weekend and my PD's clinic was closed, so on Sunday I tried a nearby clinic, also a PD. This PD took his case very lightly, just gave some medicine to stop the diarrhea and powder probiotics. No mention of dehydration. I was worried becos he was lethargic and took 3 hours naps still refused to wake up.
The next morning, he had watery diarrhea twice in the morning, I wasn't comfortable so I called my usual PD and he asked to bring my boy to see him. This PD is really good, he told me my boy was dehyrdrated thats why he kept sleeping. He told me to stop giving him the anti-diarrhea medicine since his diarrhea wasn't too serious, just let the bad stuff to come out. Prescribed probiotics and motilium to prevent vomitting. And prescribed Hydralyte to replace electrolytes lost, this contains sodium chloride, potassium citrate, citric acid monohydrate and glucose.
He also warned me that if my boy continued to be lethargic or refused to take the liquids orally then admit to hospital to put him on drips. Luckily my boy reacted well to the biogaia probiotics (i think other brands really not so good), and i managed to make him take the hydralyte together with yogurt and water. His stool firmed up and no more vomit.
Your first visit to Mt A, the doctor didn't prescribe anything to prevent dehydration? Or told you to monitor? It looks like your girl was dehydrated hence the seizure. And yes, you shouldn't put anything into her mouth if she has a seizure, should lay her on her side (recovery position).