How Can Severe Constipation Caused By Medication Be Treated?

Last Monday, I got a pilondonal cyst removed and stiched up. They prescribed pain pills that gave me horrible constipation. I've since stopped taking them but I feel as though I have a hard lump of stool lodged in there. I called my dr, and he told me to try milk of magnesia and enema. I've also been drinking lots of water. Milk of magnesia caused no result, and the enema caused a lot of liquid and mushy stool to come out. It helped, but I still feel as though there is some hard stool in there. I can feel the pressure. Is it possibly impacted stool. Could that develop just by taking pain pills (percecets?) for less than a week? In addition to this, the stiches have come undone. I've packed it with gauze and am going in on Mon to see the doc about this. He's a colorectal surgeon. Will he also be able to do anything about this severe constipation? Is there anything else I can do?