My Paint horse has started to change colour and get white blotchy spots

No she isnt a Appy, but she is a paint black and white and has been for almost 2yrs.

But now she has started to get white blotchy spots up her legs and on her face and some on her body and back. But lots on her two front legs. When she was born she was that greyish colour with 4 white stockings, a patch on her rump and her wither and one star. Now she has lots of large blotches going up her legs and around her face? Her mother is solid balck with white star, a few flecks of grey cause she is getting older. Her father was a paint black and white tobiano. Unsure of where this colouring has come from. What I want to know is there some sort of name for this and why is she beginning to change now. Please help cause it baffles me on how she is like this and why there wasnt a sign of this when she was born?

Its nothing to do with her skin it is actually her colouring of the hair. Nothing unhealthy about it at all.

Paints do NOT change colors from birth. Ever. Unless they are born to one grey parent, in which case their coloring changes are due to the grey factor. Otherwise what you see when your Paint is born for patches is what you get. This does not change whether your horse is an overo or tobiano or tovero.

Roan horses do NOT change colors either. Ever. They do not grey out. If you had a horse that you thought was a roan, and its color continues to drastically change, that it wasn't actually a roan, but a grey.

Your horse cannot be grey unless one parent is grey. Is there any chance the mare is going to grey? You didn't say how old the mare is - could she still be a fairly young horse herself? If so, she may be greying slowly which explains the grey coloring on her face. Some horse grey quicker than others, although it seems unlikely that your mare is mature enough to have a grown foal and still not show obvious signs of greying herself. By the way, most greying begins at a horse's eyes and ears.