Had the feeling of passing out quite a few times while standing or lying down. haven't done so but vomited later on & now have a headache. any ideas?

Migraine : It sounds like the feeling as if you are dizzy , light headed , maybe the prodrome to what sounds like migraine headaches ( vomited and developed a headache afterwords ) you need to see your PCP and get a tryptan such as Imitrex (sumatriptan) or Maxsalt to take at the onset of dizziness and stop the headache from progressing . If it works , this is also a test . Good luck to you finding out what persipitstes