SO sorry you are in so much pain.
I know what that is like. When I was taking painkillers before my surgery, I took 100 mg stool softener in the morning and again at night. I also took 1 dose of Miralax in the morning and I ate some raisin bread with 2 extra chopped prunes at night. I was also terrified of constipation, but even with the painkillers every 4 hours, I was able to go every morning after drinking some coffee.
Also, the last couple of days before my surgery, I did not sit at all. I layed on my belly if I wasn't standing or moving around. It's a crazy struggle and I had to truly advocate for myself, so do your best to get in to see someone and get fixed as soon as possible.

Did you have the other creme after the GTN?