My family got a bug from DD bowling birthday party on May 9th. This is very slow moving bug and it always start on us early in the evening. First DS#2 had vomited the whole time he has the stomach bug. He was down for 2 days.
I got it after 5 days, I was down over night with vomiting and diarrhea. The next day was tolerable however, I had to rest because I don't have energy and had to go to the bathroom a few times.
Then my 6yo and 4yo came down with the bug Saturday and Sunday. They had stomach ache and vomiting. That was last weekend. And DH got on Wednesday night and still not 100% until today. He had the diarrhea and did eat or drink much of anything.
Last night he was looking at his tongue and notice the yellowish color in them. We google it and sure enough he is dehydrated. The lemon juice I given him on Thursday noon helped him quite a bit. I also give him some Friday morning to ease-up his stomach. I'm not really sure about the sour and stomach ache but they work. I also had a sour soup the weekend I was sick and it help a lot.
If you have stomach ache and diarrhea try taking concentrated lemon juice to ease-up the pain. I don't have a scientific study about it but they work.