Seth- You may, especially given your age, have secondary (rather than primary) hypertension.
I am amazed your doctor hasn't run a renal/kidney scan on you to rule out kidney disorders. (Frequent urination is often a big clue here)... Also he should be testing you for other endocrine disorders. (including thyroid, as poster mentioned above)
Sometimes a tumor (benign) in the adrenal gland can cause hypertension, and SWEATING, etc. (it's called a pheochromocytoma)
Here is a Mayo Clinic link about different causes of sceondary hypertension:
[url="http://www.mayoclinic.com/invoke.cfm?id=HQ01345"]http://www.mayoclinic.com/invoke.cfm?id=HQ01345[/url]
Hope it helps.
zuzu xxx