How common are wrong side biopsies?

My original ultrasound showed a right side nodule and I was sent for a right side biopsy. It came back benign. My doctor recently requested the report and the report showed the biopsy was done on a left nodule. I don't even have a left nodule. No wonder it was benign. Well the one on the right is now very large with a cyst and my thyroid is enlarged. I have chest pain,panic attacks, my joints ache, head aches all of the time, my throat is dry, achy and it's difficult to swallow, I am hungry all of the time, at times I have double vision, blurry vision and just feel unwell. My endo. is terrible, I am the one that actually read the biopsy report and noticed that it was the wrong side, she said "benign it's fine, you just have Hashimotos thyroiditis, come back in 6 months" I said " let me see that". Then I said " look, it's the wrong side". I waited 3 months to see this doctor! She finally said that I do need a new biopsy and to come back on January 8th, what a joke. So I went to my PCP on friday and he scheduled a biopsy for me tomorrow. I am NEVER going back to that endo. again. So now I will finally get the correct biopsy tomorrow. My thyroid function is 1.16 and I usually have thyroid antibodies in my blood but it didn't show that on my blood work last week possibly because of the medrol I have been on for the past 3 month for all of the joint pain I have been experiencing. I heard that medrol can supress your immune system, is that true? I have made an appointment with a new endo. but that won't be until 1/15/10.