You should try to go and get your blood pressure checked. Anything from hypertension to other stresses that increase your blood pressure could cause tinnitus to become louder in your ear. If your blood pressure is elevated, try to do things to alleviate it. You should possibly consider taking blood-pressure medication, reducing your caffeine consumption, or just learning different stress management techniques.
There could possibly be a variety of medical conditions that could be causing your tinnitus. If you have ruled out all the common causes, you should have your doctor take a look at you and see if you have any other symptoms for other health conditions. Some ailments that could be a cause include: malformation of capillaries, Miniere's disease, and acoustic neuroma. If you happen to have one of these conditions, your doctor may be able to help you with them.