I have felt extremely ill/nauseous/dizzy with feeling of throat closing,sweating a lot/and headaches that are worse on left side. what is wrong???

Pregnanacy: A common cause of this constilzaiton of symptoms could be preganancy. The only way to know for certain is to see a doctor for a through physical exam with appropriate testing.

Headaches check up: if you have a history of migraine headaches, they can come anytime as you know. if this is the first time for you to have a headache, you will need to go to a medical facility to be checked out. the other symptoms you are experiencing can be either the body reaction of having a bad migraine or something else. unilateral headaches may even deserve an imaging study like CT scan.