What you are seeing is the failing of the LCD crystal display. Not completely uncommon and seems to have some relationship to outside temp. Mine will go from 2 dots noticed to %70 covered by what looks like a snowflake. Snowflake has only apeared once, but size of intrusion changes regularly.
Only solution I know of is to swap out the display (I just live with mine as it is mostly unintrusive as the 2 dots are at the very bottom.)
Good news it is not contagious and neither you nor the car need any meds
