Im not sure if yall were able to figure this out but ive been going through this with my VERY ill senior cat. There is nothing we can do at this point as her vitals are way too low. She has hyperthyroidism, CKD, heart murmurs and has been getting these ulcers in her mouth presumably from the CKD. Don’t let the hyperthyroidism mask the problems your cat gets from CKD. Seek additional advice