My daughter has high fevers (40 degrees) vomits and has diarrea since last night, can i wait a bit to see how it develop or should i go see a doctor?

OK to wait IF she is: alert, has moist membranes in her mouth, and is urinating. Even if she vomits, encourage rehydration fluids like Pedialyte or a home made rehydration solution made from water, sugar, baking soda and flavoring like powdered jello or koolaide: https://www.babysavers.com/how-to-make-homemade-pedialyte-recipes-and-instructions/. If vomiting persists more than 24 hours she needs to be seen.