What Causes Fever And Body Pain?

i am having high fever and bodypain for last 4 days , 10 days back i had a dislocation of my distal inter phalangial joint of my little finger , with a laceration of 3 cm , i went to a ortho doctor , he jus reduced my joint and sutured my wound with 4 stitches and gave an oral antibiotic for just 3 days , and asked me to wear the splint for atleast 4 weeks , now its been 4 days since im having severe fever with myalgia , , i want to know what could be the reason and what should i do now , thankyou