What does this sound like ?

My 2 yr old woke up 7 in the morning with fever high fever . gave her tylonol she went back to sleep . the fever went down then she woke up crying throwing up all the milk she had drank that night . hours later she was not feeling good to even sleep kept tossing turning then threw up all the apple juice she just had drank seconds ago .. Gave her a lukewarm bath she seem to feel better after that then i gave her more tylonol she started playing and everything seem like her normal self . then 2 hours pass i give her something to eat and some Pedialyte . she started laying down not looking too good fell asleep . now shes asleep but shes getting hot again like her fever is coming back . does this sound like a stomach bug or flu ? Should i take her to er or just keep an eye on her until it goes away ? I have a 3 week old too and im so scared hes gonna get sick 😩😩😭😭