TIA for any thoughts/advice.
ETA: she had stomach pains since starting to get sick, as did her 3yo sister who also has the flu...but got it earlier so is better today. The 3yo hasn't had any diarrhea though. Same dosing.
I wouldn't worry about giving her too much vitamin c . The runny stools are a good sign she has hit bowel tolerance and should start to get better soon - in fact it sounds as if she is getting better. Regarding the dosage, EVERYONE has a different amount at which tolerance is hit. I'd probably cut the dosing in 1/2 and maybe do twice a day instead of every few hours. Just feel it out.