Can urgent care write me a medical excuse?

I’m currently on probation and have to take 2 urine drug screens a month. I have had 8 appointments to date and each one was a living hell… I had to water board myself and sit at the office all day in absolute pain and discomfort until I could go. My PO said I can get a medical excuse to switch to blood testing, I just need a doctor to sign off on it and forward her a medical excuse. I tried scheduling an appointment with a primary but I can’t get an appointment for 2 months. My question is will a doctor at urgent care be willing to give me a medical excuse so I can switch to blood testing?