What Causes Double Vision And Headache?

question is for my mother, she have 69 years. She have high blood pressure, and variation in blood sugar within the limits of 4 to 6. 160cm high and 65 kg heavy. 5 days ago she has double vision, and the second picture is distorted, also has a headache. She went to an eye doctor, then she made the recording head with computer tomography CT. Both examinations showed no changes and problems. Doctors have no idea what this is about, they gave her pills for circulation, for swelling and b complex, and expect a response within the next 10 days. Can you tell me what to expect from the problem and what tests to do. Perhaps it is a brain tumor?