i dont know whether you have ever thought about mineral makeup? i use this one:
http://www.lilylolo.co.uk/lily-product1.php?ca t=4
it is by far the best thing i have ever used to cover spots, it doesnt give that horrible chalky texture over your spots that always make them look worse than if you just left them alone.
it is a fine powder you sweep over the spot, amazing coverage and lasts all day. because its made of minerals it actually helps your skin (it has on mine anyway). i could never go back to ordinary concealers now!
: )