Sounds like a stomach bug.
Btdt lots of times in 4 kids.
I just wanted to say nurse as much as your little one wants. Even if it's getting thrown up right away breast milk is do easily and quickly digested that you little one will get something at least as well as any antibodies you might have to fight it.
Don't let anyone tell you that it's like dairy and you should stop giving breastmilk.
Even some doctors and nurses are really ignorant about Breast milk.
Constant nursing was the only thing that kept one of my little ones out of the hospital and off Iv fluids during a flu in our house. Even though he was consistently throwing it back up he got enough to keep from becoming dehydrated.