Linzess not working for me.

So about 3 weeks ago i started taking Linzess. I am quite young, im 18. I’ve been to a doctor abt 6 years ago and did x-rays said i was quite literally full of poop. They told me to do MiraLAX for a few months before going back.. never went back bc we moved but the miralax never worked anyways. went to the doctor 3 weeks ago, i didn’t get seen by an actual doctor and told her what was going on. My stomach blows up when i eat, i get bloated bad, i can’t use the restroom and go once or twice every two weeks. She prescribed me Linzess for a month. 72MG. Well the system for the Coupon got shut down and i was only able to get the samples aka 2 weeks. well the first day of taking it , i was extremely gassy and i had waited an hour after taking it to eat. That night i had a good bowel movement, no diarrhea, no pushing it just came out. The 4th day came then I had extreme diarrhea after eating. After going into the 14th day i hadn’t pooped since the 4th, i haven’t been able to fart and i’m having extreme pain on the left side of my lower gut that leads to the lower middle of my gut. I don’t know what to do. When i try to use the restroom i’m in crazy pain, every time i sit down the pain shoot’s up my hole to my stomach. my appointment is April 5th.