I had a bout of gastro in the early days of BF DD.
I just kept up fluids and , fed her more reguarly and then passed her off to DH once I had finished the feed to try and limit the contact. Also all the usual extra hygene of washing hands more reguarly.
As Lime has said, the bout DD gets should not be as severe as you are BF.
A combination of offering water from a sippy cup and the BF should keep her well hydrated.
Check out the Royal Childrens Hospital or Better Health website as they have great Fact sheets on little ones with Gastro.
Hope you are both well soon