One of the first thing your father would need to ensure is that he is passing soft stools, so as not to aggravate this condition. Hard stools will make the situation worse and keep tearing at the skin, which will make the condition worse. Ensure that there is enough fiber and very little carbohydrates in the diet. Fresh vegetables and fruits, salads and herbs and only plain overcooked rice in the diet should help him considerably. You must also ensure that the area is kept clean and dry. For this, apply turmeric powder to the area. This will help to heal the wounds considerably.
Applying aloe vera gel directly to the affected area will cool the area down and reduce the pain as well. It will also help considerably with the healing. You can also place refrigerated used tea bags on the wound and leave them there. This will have the added benefit of draining out any pus as well. To keep the area dry, use a corn starch based powder. Avoid using talc, since this could cause more harm than good. To give your father relief, try to use a sitz bath with a pinch of boric powder added to the warm water. This will help to drain out any pus and will also give relief to your father's pain. He can also be made to sit just plain hot water to relieve pain. In any case, he must always sit on soft surfaces only, as sitting on a hard surface can aggravate this situation.
answered by G M