what do I do?

My daughter is 10 months old. Yesterday my she started throwing up around 9 am. I took her to the er, was in there for 4 hours all for them to not know why she's throwing up, they just have her a nausea medication and sent us on our way and told us no solids. She drank maybe 8 ounces of formula and some tea in 24 hours since then. She refuses to drink anything. And I'm worried. She doesn't have a fever or anything she's just not acting like her normal happy self. Idk what to do!  Do I take her to another hospital? Idk if throwing up is associated with teething or not, or maybe she ate something she wasn't supposed to. I just don't want her to get dehydrated...she won't even drink her pedialyte.