Sick 3 year old

So my 3 year old is really sick, it came out of the blue Sunday morning. Saturday she was healthy and happy then Sunday she woke up with a fever and a cough and an upset tummy. She was super cranky all day yesterday and then over night her fever shot right up to 40 degrees. Advil will bring her temp down slightly but won’t get rid of the fever all together. She’s very phlegmy too so when she gets crying she ends up throwing up a bunch of phlegm. This momma is stressed to the max. Anybody else have similar experiences with their kids being sick?