Thanks for this question. Skin disorders (and yes, the scalp is considered part of your skin) can be very common, very annoying, and very hard to diagnose without more information and a physical exam. That is why it is important to speak with your primary care doctor
. There are so many things that can cause a scab, let's just review a few. Obviously, trauma is one of the most common causes. If you have recently been scratched, wounded, etc, then that would be a simple explanation. It is quite common for these things to go unnoticed, and so if the wound heals in a very short amount of time, then that is usually a good sign. On the other hand, some significantly serious things can present as scabs as well. There are both infectious and auto-immune conditions that can start off with some skin findings that could be consistent with what you are describing. Even more ominous, skin cancers will often present as a non-healing scab that just doesn't seem to go away. If you have any concerns about this spot on your head, please speak with your doctor. Please seek either the assistance of your primary care doctor or a dermatologist.