Hello. Welcome to PC. I agree with Dowdy. If the fixation becomes a problem impacting your quality of life, therapy would be helpful and possibly medication. I also wonder if building new neural pathways would be beneficial. Every time you start fixating on something picture a large stop sign and replace it with another thought. Like wearing a path through the snow or wearing a trail through the woods, the new thoughts will build new neural pathways and the old ones will start fading over time. Best wishes.