Mark, I understand your frustration with these types of posts, as they happen very frequently and the answer is always the same, but as someone who has dealt with this quite severe anxiety over hitting my head, I can say with some confidence that the people making these posts really wish they didn't have to. By this I mean their brain is racked with repetitious thoughts playing out the situation, thinking about the ramifications if it is a concussion, and thoughts of the like. They understand that it is essentially impossible for it to have caused a concussion, but its that tiny .1% chance that it could that drives them to need reassurance that it didn't. Because ultimately that is what people who make these kinds of posts want. So expressing frustration at them for what technically is a ridiculous question, is not helpful. They know it is ridiculous. But their brains cannot stop playing the situation out in their heads. If these posts get tiresome to you or are not relatable, it might be best to just ignore them.

John, how I have greatly improved my obsessing over hitting my head, is really by my obsession changing. What I have noticed with clinical OCD, I may stop obsessing about one thing, but that is just because the obsession has changed. This could be similar to you IF you have clinical OCD, as in the concussion you sustained caused damage to the part of your brain that controls compulsive thoughts. A part of the brain that when damaged seems to lead to OCD symptoms is the Basal Ganglia. The second possibility is that your obsession over this is more PTSD induced. This would be more possible if you have hit your head multiple times and had clear worsening of symptoms from each concurrent time. Your brain would begin to become extremely fearful of potentially hitting your head again given your past history of multiple hits and the clear worsening they caused. It could also be a combination.

If it is either of them, the best thing you can do is probably try to get CBT with a focus on exposure therapy. Also what I noticed whenever I would tap my head or touch it accidentally with a mild amount of force is that my symptoms would be worse from the anxiety reaction for about 1-2 days and I would be obsessing over it for that periods duration. After 1-2 days, I always knew whether or not it was a real concussion because whenever I had a real concussion the symptoms were very clear. But whenever I had a real concussion it would sometimes take a full day or 2 for them to manifest, so that is why it took 1-2 days for the anxiety reaction to subside.

One last thing to consider is that if you do have clinical OCD, the only way that I have found for it to truly subside is to truly not care about the thing you are obsessing about anymore. This can't just be a conscious not caring, it has to be complete subconscious not caring as well. Right at the beginning of sustaining my head injuries, my OCD manifested through obsession over having a heart attack. This was caused by having chest pain induced by anxiety caused by taking Piracetam, which is a Nootropic. At the time I did not know the Piracetam caused this, so I genuinely thought there was something wrong with my heart. I got testing done on my heart, and all was fine and dandy, but the pain persisted. I was not convinced there was nothing wrong with my heart after these tests, but eventually I got so mentally tired and just generally fatigued with the whole thing that I stopped caring. I had to stop caring about whether or not I would have a heart attack and die for the chest pain to go away. Basically, I had to subconsciously not be anxious about my heart for the anxiety that was causing that pain to go away. I state this just because it could be the case with you as well. You may have to try to come to terms with yourself mentally to where you do not fear hitting your head again. This doesn't mean you wouldn't be anxious about participating in risky activities like contact sports, etc. again. But more-so that you would come to terms with the fact that if I nudge my head a little bit shampooing my head taking a shower, then so be it. You have to try to come to terms with yourself consciously and subconsciously with this whole situation so that you can no longer be fearful of these innocuous hits.