My bb girl also have experience of 腸胃炎 few months ago !
I remember she also 每日平均痾3-5次,
The doctor had given her 豆奶&營養POWDER開水!!
So, she recovered within 3 days.
I think it is better to take your bb 睇另一個醫生!!
( if U need the information of the doctor, pls pm me. The doctor is at Mei Foo)