My Boyfriend Recently On Saturday March 26 Twisted His Knee

My boyfriend recently on Saturday March 26 twisted his knee he hasn't been able to get an MRI because of the swelling. Possible broken ACL and Muniscus.. He is on 800 mg of ibuprofen and hydrocodone for the pain both I which he has taken before, with no side affects. This morning he woke up and his body was beat red. And he said he has a burning sensation. What could be causing this?