Do I have the stomach flu or something else? What can I do?

I haven't been feeling well for over a week now. At first, my noticeable symptoms were just:
-Insomnia (I couldn't get more than 5 or 6 hours of sleep every night. In the early morning when I hear sounds, I wake up and I can't fall back to sleep)
-Dizziness
-Nausea

In the recent days, besides all the old symptoms that still persist, I also have:
-Pressure on my chest
-Seemingly faster heartbeat
-Noticeable weakness
-Small appetite (most of the things I eat makes me feel nauseous, including water)

I don't have the energy to do any kind of activities. Everything I do seems to make me feel more nauseous (including lying in bed)

I DON'T have abdominal pain, but it seems like I have a lot of gas in abdomen
I don't have diarrhea, but my stools are a lot softer than usual.

It might be helpful for me to note that I'm probably still jetlagged after I got off the plane after a 18 hr flight about a day or two before all my symptoms started. But I doubt that everything is due to the jetlag

i'm really not that sure, but maybe it's because you're just adjusting to your regular routine. where ever you were, you probabbly had a different routine and you went back home and now you need to adjust back to your original routine. another thing is that the place you went to, maybe the food or water is different. maybe your about to have your period or something. i highly suggest that you go to a doctor and the doctor will find out what's going on. good luck and take it nice and easy. =)