It is possible, Thyroid meds are funny, what works well for one does not work well for others, I was on (Generic
for six months and my labs did not budge, then went to Synthroid (brand
Name) and had better sucess, my endo claimed that generics were not as consistant as name brand. Pharmacy said they are the same? So the change may have made a difference, some times the fillers they use can cause issues also.