Is the purification performed by the questioner after urinating and the discharge of prostatic fluid (madhy) correct, and is there a simpler method of purification, taking into account the skin diseases he suffers from because of this?

We congratulate you on abstaining from masturbation, and we advise you to ignore obsessive thoughts. If the urine stops after 10 minutes, then wait for it to completely cease. Assuming that impurity has affected your garment or body, then wash only the area where you are certain the impurity is present. You are not required to wash an area whose contamination is doubted, because the default state is purity. What you used to do, washing the penis and the surrounding thigh area, is incorrect.