What Can Be The Reason For Sudden Pain After Surgery?

Ihad a synovial cyst of the lumbar spine surgical excised... I am 8 -9 weeks post op .... After surgery all radioculopathy was immediately gone..... Pain is now back and proressing up the pain scale..
Had MRI yesterday ..will see surgeon today... He is ortho/neuro surgeon.... Great, knowledgable, professional surgeon ... I Suspect herniation or
abscess......... My question is what could the
abscess.. I am a practicing certified family nurse practitioner interested in returning to work ASAP. Would like to better understanding of the process to know what questions to ask my doc todAy.... Your help is greatly appreciated........