This sounds like OCD (I am not a doctor; this is just what I've learned based on my personal experiences and from speaking to others) in the form of, as you say, intrusive thoughts; it's somewhat of a subcategory of OCD: obsessive compulsive disorder. Have you ever been diagnosed as someone with OCD? Have you taken an OCD test here on Psych Central?

I'd suggest looking the forum OCD & Trichotillomania.

I have OCD. Intrusive thoughts have plagued my life since I was a young teen, and I'm now 30 years of age. I have CBT for my OCD and went to an OCD support group a few times. Although these things helped, it didn't cure me. It's not the same for everone, sadly. Some can be cured, but some get the tools needed to cope better. I was the latter.

If we are talking OCD, and what I've learned about intrusive thoughts as per my case (just in-case coping methods differ from case-to-case) is appropriate here, then I would suggest the following:

That you continue to use distraction techniques. Consider working on your anxiety levels too, because high anxiety can antagonise the brain, causing more of these intrusive thoughts to pop up. Perhaps talk here about ways to lower and/or cope with your anxiety (if you do struggle with it) maybe in the Anxiety, Panic and Phobias forum. My OCD is always worse when I'm anxious.

I would also suggest that you absolutely do not try to fight the thoughts, but allow them their place, accept that they are there, that they are nonsense thoughts that many if not all of us get, then move on. Of course this is easier said than done, which is why it takes time and a lotta work. It will be difficult at first, if, like I was, you're used to fighting the thoughts. I tell them to sod off, that they are nonsense, I laugh at them, or I simply distract myself using my senses, such as smell and sight.

Maybe think of intrusive thoughts as an attention-seeking child: were you to ignore the child, he or she would get bored and give up, figuring that you won't pay attention to them. That's how I see it, at least. The more attention you give to the child, the more the child will persist.

Hope this helps you as it did me.