Your father definitely has a problem First diabetis...renal impairment ...and now diabetic foot. Remember diabetic foots do not heal well. 80 % foots will have another amputation within 5 years.
You stated water and blood coming out. Well it has not healed and my be extending to other parts of foot.
Next Steps
consult surgeon and diabetic footwear maker
Health Tips
1. Footcare in diabetis mandatory.
2. Diabetic Footwear is compulsory
3. Learn correct dressing.
4. Healing takes long time
5. Apply Diafoot SB ointment to both feet at night. It prevents cracks developing which is the sourse of infection.
6. Never to walk barefoot