What is happening to me?!

Last Monday I was sent into the emergency room by ambulance because I vomited about 10 times in 4 hours. I was released after a 4 hour stay at the hospital. After the blood work and etc. They diagnosed me with food poisoning or catching a viral infection. I felt better and stuck to eating soup and some more soild foods slowly. I was to have a follow-up blood test within a week.
On Friday, I felt nauseous, had a head ache and felt sick. I thought it was a fever so I started taking Tylenol which only helped the headache.  
On Monday, I went to my family doctor to get my second blood test. My family doctor told me to take Gravol, which at first worked great that day! 
But today, Tuesday, my body became immune to Gravol or somethig and has gone back to feeling nauseous :S 
I feel like I've been hindered from my normal life... And at the back of my mind I've been stressing... Wondering if I'm pregnant... which will not be pleasent news for me D: But also how did i get pregnant if I always use condoms and they never broke or anything before.
I would also appreciate any advice on treating nausea please