Walgreens

My doctor gave me a prescription for chronic pain. I am unable to walk without the pain medication. We are discussing back surgery to alleviate some of the pain but in the meantime, I have to take oxycodone.
I originally went to the store on Oakland Park and University in Sunrise, Fl. They were closed for cleaning a couple of weeks ago and the service at that store was too slow, so I changed my doctors and hospital records to reflect a new pharmacy on Nob Hill and Sunrise, in Plantation, Fl.
Today I brought my prescription into the Nob Hill store, and they collected my driver's license and prescription and were told to go sit down. A few minutes later the pharmacist called me to the counter and said we don't have these pills and handed my script and DL back to me. I asked where can I go to fill this? The clerk at the counter started yelling at me, saying you cannot keep changing pharmacies all of the time. What? That was the first time I went to that store after changing my pharmacy hospital and doctor records.
I was in so much pain as I stood there, and they embarrassed and humiliated me in front of all of the customers. They acted despicably. Is there a rule saying I can only use one pharmacy?