In your circumstances a cleansing enema shouldn't affect nutrient absorption, but should help greatly in assisting your bowel movements. I would encourage you never to let yourself go for 4 days without a BM.
Initially, I would suggest one or 2 full bag salt solution enemas tonight, and once a day for the next week or so to try to cleanse your entire large intestine. After you are cleaned out you can try some smaller volume enemas, but I wouldn't let myself go more than 48 hours without a BM under any circumstances.
Your skin will be one of the externally visible beneficiaries of regular bowel movements, but your entire body will be healthier and you will feel better with more energy once you establish regularity.