been sick and not sure why

so i haven't been on the boards in forever.  I've been on an unfortunate slippery slope that I've done nothing but make excuses for.  I've been stressed after dealing with my dads death.  i even quit my second job because I've been so sick and exhausted.  so here i am working to get back on track with food and gym shopping.  now the main reason I'm seeking help with you guys is cause I'm kind of at a loss.  mainly at lunch time when i eat i get so lightheaded that i want to puke or pass out.  Ive been annoying the hell out of general practitioner trying to figure out why Ive been sick for months especially with this new development.  now I'm being sent to an sent and getting a barium swallow study done.  she thought it might have been an blockage and I'd need an egd but i know that's not it Ive had two of those and never felt like this.  has anyone had this happen any ideas of what i should be looking/asking for.  i did have my labs done back in November and my vitamin levels are fine.  that's the one thing i haven't managed to screw up in a while.  any help is appreciated

Could it be reactive hypoglycemia?  If you have a glucose meter handy try checking your blood sugar and see if it is low.