I been vommitting periodcally for about four weeks.Can't keep any liquids or soilds.And I been light headed.

If you have been vomitting that much. And you can't keep liquids down, you are probably very dehydrated. Do you have the runs as well? This condition is very damaging to your kidneys. I would advise strongly that you see your healthcare professional immediately.

Is it possible that you are pregnant?