I am suffering from a dermatological disease in my feet causing parts of the skin, especially under the toes, to protrude and partly separate from the rest of the skin. Knowing that this is very difficult, is it obligatory to make the water reach under these parts? To avoid doubt, I depend on pouring a large amount of water, in order to make sure that water reaches under these parts. Also, I am seeking treatment for my feet, but this may take much time. Please advise. may Allaah reward you.

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

If the skin is protruding but without cracks, you have to make sure that the water reaches only the surface of the skin. But if there are cracks, you have to make sure the water reaches under these cracks, if this is not harmful. Al-Baji a Maaliki scholar, said: "If the scar of the wound is apparent, water must reach it, such as the place of amputation on the elbow and feet."

An-Nawawi said:

"Ash-Shaafi‘i,  in Al-Umm, and Shaafi‘i scholars said: "If one's fingers or toes are not separated naturally, he does not have to separate them by cutting. Rather, it is impermissible to do so, but he has to wash the visible parts." The Shaafi‘i scholars stated that if there are cracks on the feet, water must reach inside these cracks." 

If you doubted whether water reached the surface of the skin in these cracks during washing, then you have to wash again. If these doubts occurred after Wudhoo’, then pay no attention to them.

Allaah Knows best.