Losing hair

I have a male Maltese that is losing all of his hair . Has anybody on here had this problem .We had him groomed at Petsmart about a year ago and that when it started . He all most bald took him to my vet and she did a blood test said his Thyroid was low and put him on some pills for it but it not helping . So thought i ask on here to see if any body knew of something else i could try.