What foundation has heavy cover?

My face and neck are heavily covered with white blotches from an illness. I have spent so much money on makeup that is supposed to cover but the white blotches always show through. I am so self conscious that I keep my hair length & style so hide them & never wear my hair up! The only makeup I found that actually made my whole face the same shade is Igia Instant Cover and I can't even find it any more. By the end of the day my face always felt really dirty. On the plus side, it only took a little and the white splotches didn't show through at all. I have spent a fortune trying one brand of foundation after another but nothing seems to hide them. Can anyone tell me of some kind of foundation I can use?