my husband had two knee surgeries 4 weeks ago. he was on morphine for the 7 days he was in the hospital and has been on 1 oxycodone 10/325 every 4 hours for 3 weeks. he also was on coumadin for 16 days and had his last dose 6 days ago. he has cold sweats, back/ankle pain (but no knee pain!). is this oxycodone withdrawal and how long will it last?