Head Light Flight

So i just got back from a trip from the bahamas last night and on the day we left for home I felt light headed and weakish. On the flight back home I really felt light headed and weak and the flight back home was a 5 hour and 30 min flight and the time difference goes back by 3 hours (i live in Cali). Do you think im dehydrated? cause it was really hot in the bahamas and I didnt drink a lot a lot, but I did drink pretty well. Could it be that im jet lag? maybe tired? I slept pretty well last night and I still feel light headed and weak.

also:
-today i would feel really light headed/weak and it scares me, and I felt like I was gonna pass out
-i ate a lot of food today, so im not hungry.
-do you think food might be an issue? like i ate some junk food at the airport and on my vacation so you think the food might do something? I didnt feel like this til I got back from the bahamas (and a little the day before).

please help , thanks !