I'm afraid I can't say much from your description. Here is a guess: when your mother gets the sores, does she itch or pick at them? If she does, they won't go away unless she stops. Beyond that, I can't recommend anything except for another opinion. If she goes for one, make sure all previous records get to the new doctor first, so the same tests won't have to be repeated.
Sorry I can't say more than that.
Dr. Rockoff
I had severe skin disorder like that because of hypothyroidism. Skin disorder can happen in hypo even before labs go out of range.
Have her get full thyroid function tests:
Thyroid Antibodies
TSH
Free T4
Free T3
esp. if she has other hypo symptoms like fatigue, weight gain, menstrual problems, etc.