Hello I'm not a doctor but a mom and a health care provider, reading the symptoms and especailly you child having diarrhea
that has lasted over a week with fever
is very concerning....I would take him to the Pediatrician
tomorrow morning and have her/him do blood work to identify what's really goin on....if you're near Children's Hospital I would do it right away...don't wait any longer...the poor child has already suffered enough! good luck!