I am sorry to hear that you have a bump on your face that continues to scab up, and itches, and that you are worried about what it might be. I am happy to give you some general information about skin lesions on the face, but ultimately I am going to recommend that you make an appointment with a dermatologist
or an ENT (Ear Nose Throat) physician to get evaluated. They will be able to take a medical history (including sun exposure) and examine you thoroughly (which I am unable to do in this setting) which will allow them to give you more of an accurate answer. Depending on your Fitzpatrick score (a scale that is used by physicians to describe how pale, Fitzpatrick 1, or dark, Fitzpatrick 6 your skin is) there could be different etiologies of a chronic scab. For instance, pale skinned caucasians with a significant amount of sun exposure are prone to developing actinic keratoses, which are abnormal areas of squamous skin cells that secrete keratin (a fibrinous material that makes your skin water proof). These areas are scaly and dry typically. Of course skin lesions that scab up can be much more sinister (like a basal cell carcinoma or a squamous cell skin cancer) One thing in particular that I would be worried about with a chronic ulcer
that is crusting is something called a marjolin's ulcer that can harbor a squamous cell carcinoma. This is what it is worth getting checked out by a physician.