Am i starting to get sick?

So im kinda scared, my stomach has not been feeling so well, it will hurt, go away, and come back. I have the BIGGEST weekend that will make my career and i can NOT get sick. I woke up at 2:30AM last night with a stomache ach feeling like i wanted to throw up! But i went back to sleep, when i woke up in the Morning my head hurt sooo bad! My neck hurt also. I got out of bed and buy 2: pm i felt good, my head nor my stomach hurt, now its 10:00 at night and my stomach is starting to hurt, i have bad gas (feel hot and it smells bad) I know this may sound funny and all but i got to be ready for this week! Some please help!