Call the medical provider(s) who ordered and/or performed the biopsy and report the symptoms.

I'm sorry to hear that, it might be nerve damage due to the biopsy. Since I had my colectomy 16 years ago I have suffered from anal spasms, ranging in pain from a feeling of heaviness and discomfort to agonising pain which literally stops me in my tracks. 

I'm in the UK and this past 6 months the "attacks" have increased in frequency. I requested an urgent outpatient appointment to see my surgeon. I finally got to see him 9 weeks later. He was not my usual "guy" so I was describing my symptoms again when he raised the possibility of a condition Called Proctalgia Fujax. He gave me a load of research material which definitely appears the same as I am suffering from. Sadly there is no cure, however the symptoms can be "managed" he is going to give me a thorough examination under general anaesthetic to check for any other reason for the pain and if , as he suspects none is found then he will diagnos proctalgia fujax. 

I don't know if this info will do you any good but it's probably worth googling it anyway.

good luck with that and fingers crossed your prostate biopsy is clear also.

kind regards 

Sylvia