I Have Been Resantly Released From Prison My Belly Was

I have been resantly released from prison my belly was large and tight with puss in my belly button,I've been to the er the took X-rays and a rt scan with samples of the puss.test results came back negative.the gave me antibiotics and it seems to be doing much better .its been 2 weeks but there is still puss in it . What can I do or what is the next step may I ask? A clinic has asked me to get a MRI ,, do you think that is nesssssary ? What should I do?