Hello my father who is 65 years old feels giddy while walking. His medical history is as follows: Had angioplasty 12 years back. His blood pressure within normal limits He says he doesn't feel shortness of breath. All his blood parameters looks okay from a recent blood test. 6 months back he was detected to suffer from hypo thyroidism and is taking medication for this. Would you please suggest what type of problem could this be? what kind of tests would you recommend to find the problem?