I'm sorry if you are having these. I think we all have irrational thoughts and fears from time to time. I'd think about how frequent they are and if anxiety is the result. I agree that a little more information would be helpful. Schizophrenia is more in the realm of things like hallucinations rather than just strictly irrational thoughts or fears or even basic paranoia. So, am not thinking that this would be a concern here.
Irrational doubts could be GAD.. generalized anxiety disorder. If you are not seeing or hearing things that I doubt that it is Schizo. You could have derealization or depersoanlization.