Your comment about finding a cause for your symptoms struck me. I wanted to offer you a possibility: hyperparathyroidism (HPT). You are the right age and gender for this disorder. It strikes about 2-3% of the population each year.
Everyone know that they have a thyroid gland, but we all also have 4 parathyroid glands. They are responsible for maintaining the level of calcium in the body. In HPT, there is too much calcium. The most typical symptoms are: insomnia (including not feeling rested when you wake up), constipation, nausea, heartburn, excessive urination, memory problems, unrelenting fatigue, confusion, bone loss, and bone or joint pain.
Two blood tests are normally used to confirm the diagnosis: calcium and parathyroid hormone (PT). What most general practioners learn is that both have to be out the normal range for a diagnosis of HPT. Unfortunately that is not true. Endocrinologists that deal mainly with diabetic and thyroid patients might also be in the dark about this as well. Calcium can be normal and PT high. Google normocalcemic hyperparathroidism and you'll see what kind of research has been done on this subject. You can also have high calcium and normal PT, but that is not as common.
If you want to get an idea if you might have this, then vary your intake of calcium and vitamin D. If you feel worse with an increased intake and better with a reduced intake, then it is certainly possible that you have HPT.
The treatment is surgery.
Hope this might help you feel better. Let me know if I can answer any questions.