"I'm sick" can be as minimal as motion sickness, like being temporarily dizzy and queasy. I'm going to be sick= I am going to vomit right now " I'm ill" usually indicates poor physical health, it can be very general, ranges from a runny nose, cough, and sore throat, to a very severe illness and being bedridden. Some people interchange the word "ill " with "sick".

feel better soon . Just kidding :)