Is Persistent Pain After A Sebaceous Cyst Removal A Concern When There Is Blackening And Increased Nocturnal Discomfort?

I had a sebaceous cyst in my butt, and got it removed. Dermatologist said the entire sac came out. After 5 months of cyst removal, i felt some pain while sitting for longer time. Doctor gave me injections in that area saying lessions would have formed and this should reduce your pain. But, however, pain remains. The cyst place has become black. and pain is more in the night. anything to worry about. Please let me know doctor. Please note: No growth in that area.