Your father may have
1. Diabetes Mellitus
and Diabetic Foot
additional symptoms may include increase thirst and hunger, for that first of all you have to get his blood checked for glucose
(FBS/RBS), if tests are abnormal then oral hypoglycemic agents would be prescribed. In Diabetes, Feet are vulnerable to get affected and infected, so every diabetic patients need to take full care of his feet, wash it regularly and use proper soaks and foot wear.
Enlargement of prostrate gland is an old age abnormality leading to urine frequency, hesitancy, poor urine stream and feeling of incomplete urination. To exclude it Doctor needs to physically examine the patients, for this condition foot problem is separate entity and needs proper investigation of infections.