Golytely for severe constipation?

I've had severe constipation for 6 weeks. Going on 2 weeks with no bowel movement. Went to doc today. He did a rectal exam and there was no stool at opening. It's mostly up above. Feels like a lot of pressure and like something is stuck near gallbladder area. I had it removed in 2007. Doc said entire colon was impacted with stool. Not sure if it's an obstruction yet. He diagnosed obstipation. It's a severe form of constipation. He prescribed 1 gallon of golytely bowel prep. It's what they use before a colonoscopy. I was just reading drugs.com about it. It said "do not take if you have severe constipation or obstruction." It could cause a life threatening condition. The doc said if this doesn't work, I have to go to the hospital and be admitted. It's the weekend and I have no way to get in touch with him. Do I go ahead and take it in the morning?