I always think I am doing something wrong or bad and that I should be ashamed of myself. I always think that what I do effects the outcome of my day, so if i do this, something terrible and unrelated will happen to me and the rest of the day will be ruined. these things are simple everyday things, such as if I eat this, or if I don't do something small, like brush my teeth. and I know that I am doing this to myself, but I don't know how to get rid of these thoughts!
What yo are describing sounds like OCD (Obsessive-Compulsive Disorder). Having these sorts of obsessive, fear-based thoughts can cause a lot of misery and suffering, and it can be very hard to change on your own. Psychotherapy can be very helpful, if it is specialized to treat OCD. EFT - (my typical recommendation) is another excellent method for decreasing these thoughts and behaviors. It may be best to do this with the guidance of a trained EFT Practitioner with experience working with OCD and Anxiety Disorders.
You could try it on your own, but you might not use it in the most effective way and you may end up feeling frustrated with it if it doesn't work for you. With a good therapist, EFT could be a life saver.
Help is out there. Don't give up.