My low iron levels have actually gotten worse after being put on a iron/vit c regimen. Besides bleeding, what can cause and sustain such low iron?

Serious stuff. The very fact that you're a man who's iron-deficient in the first place is worrisome unless you're a non-supplementing vegetarian. You've got hookworm, a stomach ulcer, stomach or colon cancer, gluten enteropathy, whipple's, or something similarly nasty until proved otherwise.