I Feel Light Headed All The Time Like Just Sitting

I feel light headed all the time like just sitting and then I move my head it happens or of I bend forward and back up I get light head. I could even just be sitting there and ill get light headed and feel weird in my head. It makes my eyes feel funny in a way I can't really describe or I don't know how to describe. Like I can see but they feel funny. My stomach feels weird. And I'm shakey and when I walk I feel funny too. Like I can barely support myself almost. Or I'm going to fall over. What's wrong with me??