<s>[INST] I am a 38 year old male. I am recovering from mono (6 weeks) out. I have a pain in my back that wraps around under my my rib cage. I have had it for several months. What is the cause? I have had bloodwork and all of my cbc panel has returned normal. [/INST] Hi, Thanks for your query. The pain at the bottom center of the rib cage could be due to a renal infection or a stone if the pain does not seem to be muscular in nature. This can be ruled out after getting an ultrasound scan done. If the pain is aggravated with deep breathing or coughing then a rib injury or a muscular sprain is likely. The other causes that need to be ruled out include lung infections like pleuritic. Stopping smoking might help in reducing the symptoms do hope that you have found something helpful, and I will be glad to answer any further query. Take care </s>