purple sores on cheeks

Developed sores in my mouth.  They have persisted lasting for a week or two then going away for 2-3 days and coming back. This has gone on for more than 23 months.  They start out as purple dots and then turn to canker sores.  My face and scalp is also quite itchy.

The lesions move around a bit in my mouth from cheeks to the gums at the very back of my lower molars. But will not go away.  There is also a line on each side of my cheek.