Scurfy to me, means a waxy dandruff like when a horse has a winter coat, it is offend difficult to remove with a brush and usually have to bath to remove. Baby wipes work too.
In this case I would wash the legs really well with a antifungal or disinfected of some sort. Remove all the winter coat and remove any matting at the hocks or pasterns. If you have to clip down the legs, Belgians generally don't have a large amount of feathers in the summer, make it easier to treat or see anything wrong. Though that might be hard if she's nervous of her legs being handled.
Older drafts get side bone easily, if the lumps are near the hoof, nothing to worry about nothing can be done. If not she could have knocked herself causing calcification around the tendon (my mare as four or five lumps various sizes because of this, before I got her, cleared by vets for normal riding though).
Chestnuts don't bother me, cut off with sharp scissors or get the farrier to trim them. Or put Vaseline on them until soft enough to pull off.