My kitten is sick and i don't exactly know whats wrong.?

My kitten Saia is sick and my mom thinks that it is dehydration. She won't eat or drink anything and last night she threw up 2 times. The first time she threw up it was white and kind of foamy. The second time she threw up it was yellowish and foamy. Another thing is she usually has some meat on her bones but now she is extremely skinny and she got that skinny in a matter of a day. Right now we are giving her pediatric Electrolyte and water every 15 minutes to keep her hydrated. Also every hour we give her kitten formula so that she has something in her stomach besides just water and pediatric electrolyte. Please if there is any information that you can give me about what could be wrong with her please let me know. Your answers are greatly appreciated. Thank you.