Hi, Noted your history and understood your concerns. Well, knee replacement surgery will need some sort of medications for pain of which Hydrocodone is usually given. Although it is not common for constipation to occur with Hydrocodone, there are other associated factors that can cause constipation such as less diet, dietary changes due to pre- and post-op preparation and follow up. Hence first of all stop Hydrocodone and shift over to another anti-inflammatory with analgesic action. Revert back to normal diet. Sitz bath will be difficult as you can not sit in a squatting position. Take Laxatives and stool softeners and continue the one that suits you and has an effect. Send stool for lab test as it is showing mucus also and get treated according to the reports. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. T Chandrakant, General Surgeon