I heard from my boss this morning that she couldn't come in today. -- ***Correct sentence~ ^^ 

He keeps making mistake since he entered.

Better say: He has been making mistakes since he entered.

My son was throwing up last night, so I called 911. ***Correct sentence~ ^^ 

She don't like drinking but she drunk a little too much yesterday because she broke up.

Better say: She doesn't like drinking, but she drank a little too much yesterday after breaking up.

I'm afraid if he drinks more than he can hold. ***Correct sentence~ ^^ 

I kept her from drinking a lot, but she didn't listen to me. she ends up to get hangover.

Better say: I tried to keep her from drinking too much, but she didn't listen, and she ended up with a hangover.

I always have a stomach flue three times a year.

Better say: I always get the stomach flu three times a year.

My sister ordered chicken tender that she couldn't even eat all of them.

Better say: My sister bought so many chicken tenders that she couldn't finish them.

When the entree is served? I told you that I worked for 10 hours without lunch! 

Better say: When will the entree be served? I told you I worked for ten hours without lunch!