Is what I am doing, praying and supplicating to Allah for my recovery from a chronic skin disease that doctors have determined is incurable, correct?

Allah Almighty has sent down a cure for every ailment, and for this reason, you should not despair of finding a cure for your illness. Supplication (Du'a) and earnest entreaty to Allah are among the most powerful means of healing, as happened with the Prophet of Allah, Ayyub (Job), peace be upon him. Your turning to Allah should be in compliance with His command and out of desire for His Paradise and fear of His Hellfire, and not solely for the purpose of seeking healing.