Have many people not noticed they were infected by vampires until its nearly too late?

:D

well since im a werewolf i stopped checking

how are u supposed to tell. i keep getting comments saying i dont look so good, but i dont know what to do about it

Yeah I used to have that happen EVERY playthrough of Oblivion.

However in Skyrim I am a werewolf so it can't happen.

pray at a shine or potion of cure disease

For the major diseases like this there needs to be an immediate visual marker on your screen.

Go to the magic section of the menu, roll down to active effects and see what you are being infected by. All your positve and negative effects are listed there. You prolly just need to cure a case of Ataxa.

k thanks guys

and there was me thinking having a lie down in the inn at whiterun would solve it :/

Haven't missed a single one. There's a distinct magical aura that displays over your avatar when diseased and of course the text in the top left. Obviously, if you're in 1st person you probably won't notice the aura but I can't see how you could miss the text.