What are the common causes of dizziness, double vision, and ringing in ears?

There are several... Dizziness and ringing in the ears can come from an ear infection or swelling. Double vision is usually not associated with the above. Medications can also cause these symptoms. There could be an infection, swelling or other cause that ties all three together. It is important to be seen by an eye doctor or general doctor to get to the bottom of this.
See doctor ASAP. Tbe symptoms sound like a neurology problem. Double vision is almost always a problem with the nerves from brain to the eyes, cranial nerve 3, 4, 6. Dizziness or vertigo almost always related to balance system connected to cranial nerve 8. Ringing of ears is related to hearing also nerve 8. Anatomy wise nerve 6 and 8 in proximity. Gradenigo syndrome affects 6 and 8 but also 5. See neurologist.
Low blood pressure. Those three symptoms together make me think of low blood pressure or fainting. The ringing in the ears can go along with dizziness in many inner ear conditions but none of these conditions include double vision. You should start by seeing your primary care doctor for a complete physical.