When my PCP was monitoring levothyroxine dosage, she went with the standard guidance for the TSH levels. When my care was transferred to an endocrinologist, she required a much lower goal for the TSH levels (under 2.5) and increased my dosage of levothyroxine until I met the goal. My dosage was ultimately increased from 75 mcg to 100 mcg. And I feel much better now. So I would recommend having an endocrinologist care for your thyroid issues, not the PCP.

levothyroxine dosage is a very likely culprit, but Vitamin D, ferritin levels should also be checked.