Which ones? Most often it can be from allergies or secondary infection. I believe, though, that sometimes it can be neurological in nature too, such as having a spine pinching a nerve some place. A long shot is a nutritional issue, such as B vitamins levels issue.
Which ones? Most often it can be from allergies or secondary infection. I believe, though, that sometimes it can be neurological in nature too, such as having a spine pinching a nerve some place. A long shot is a nutritional issue, such as B vitamins levels issue.