Warfarin Sodium and neurologist

My father has been taking Warfarin for 13 years now 2.5mg a day. He's been complaining of headaches, heavy feeling in his head, dizzy spells, extreme fatigue,swelling of his legs, spontaneous numbness of his fingers, blurred vision, cold hands and feet, loss of balance and memory loss. I have spoken to his Doctors and no one believes him that the Warfarin is doing this to him. By the way, he was diagnosed with AF 13 years ago.

Does any one experience the same symptoms? what can he do? he is 77 years old.