hello, pain in between scrotum and anus is a symptom of prostitis. sometimes pain is associated with lower back and penis also. do you have other features of prostate infection? Which are fever, painful urination ,painful defication, painful erection, and increased urinary frequency. if so it is more likely bacterial infection. better get your urine tested. regarding the nerve damage, if there weren t neuronal damage at the time of injury it is unlikely you developing new nervous injury, unless you had spinal injury also with the accident. Hope this helps. Thank you