U r 53 yr old that could be the reason,because in perimenopausal n postmenopausal women have excessive dryness that would cause Asteaotic dematitis. U have RA that also cause dryness. Other possibility is dermatophytosis
. Do skin scraping for KOH mount for fungus AFTER CONSULTING DERMATOLOGIST
.Usually the medicine take by u not cause these type of lesion.U r discussing ur white spot that is very commonly seen in patient of autoimmune disorder. If they r nonprogressive no treatment require or u add antioxidant diet /cap .