I'm An RN And I Presently Have A Pt With

I'm an RN and I presently have a pt with kidney failure, lymphedema, chf, and possibly pneumonia. His body temp, however, is extremely low (using our temporal themometer-only option). It is 87.7 F or lower. Rest of his vitals are WNL. His trunk gets very sweaty but his head is very cold to touch (hense the temp). He is A&O. WHY and HOW is his temp that low??