Though I cannot be certain, your symptoms seem more characteristic of obsessive-compulsive disorder (OCD) than schizophrenia. In fact, it’s relatively common for individuals with OCD to believe that they have schizophrenia or another condition.
I would recommend seeing an OCD specialist. There are many effective treatments that could help decrease your symptoms or eliminate the disorder. It seems to be an “off and on” problem for you. Receiving formal treatment by a trained specialist could help to eliminate it from your life. As you noted, OCD does not simply go away. For many people, it becomes worse over time.
The find help tab, at the top of this page, can help you locate a specialist in your community. You may also want to read about OCD. One of the best and most effective treatments for OCD is exposure prevention and response therapy. Try to choose a therapist who has received training in that particular type of therapy. I wish you the best of luck.