My husband had surgery 4 days ago and is on Oxycondone for post-surgery pain. He has been severly constipated since the surgery. He normally eliminates 3-4 times a day and hasn't been able to go for days. He has been taking a stool softener twice a day since the surgery, but to no avail. Today he took an enema, but still with no relief. How often can we safely repeat the enema in hopes of getting him some relief?