Hi. That does really sound like anxiety disorder. Everything is bad and impending doom type of thinking? Well, I need to say this. Everyone has anxiety. Literally everyone worries and sometimes for no good reason. But they cope and move on. That's not so much a disorder as just is what it is. However, it becomes a disorder when it hampers your life. Does this impinge upon your daily life? Do you feel crummy because of it regularly?
Schizophrenia has really specific characteristics and I don't really sense that from what you are saying. And phobias don't really seem to fit either. Anxiety seems likely. But it is really important for you to find out what medicine you took. Can you call and fine out? That would be helpful. You took it just once? Or you were taking it? Or you take it all the time now? Was it a pill? shot? You as the patient have a right to know your health record so I'd call the place where it was given or the person who prescribed it and find the name.