Yes I know exactly how you feel. I get this feeling of excessive worry and guilt, I"m always thinking there's something I forgot to do. Then I won't rest till I figure it out, and like you it may of been something small, but it may of been something really important I forgot to do. My doctor said I have OCD tendancies. But that feels like anxiety is a bi-product of the obsessing, and I know I have a bad memory and poor focus so there's a good chance my worries are justified (in my own head). I try to remain focused with important tasks, taking a mental photo of what I'm doing, so later on when I suddenly think 'oh did I remember to do that' I can see it and say yes that's right, I did. I am still struggling though.