Hello My Son Is 2 And A Half. He's Been

hello
My son is 2 and a half. He's been in the hospital for 8 days. Doctors se to be unclear what is wrong with him. He spikes a very high fever at times 104.5. He breaks into rashes when fever starts. He was vomiting and had diarrhea but this seemed to have stopped. He did have a stiff neck but no longer has this problem and has been tested for meningitis and results were negative. They completed for the third time CRP and ERS tests and the last was positive for inflammation and his numbers were at 174 which is very high for his age group. Doctors are still unsure what it may be and have also ruled out Kawasaki. At this time I'm starting to wonder if possible has Rocky Mountain fever as a result of Lyme disease. Please assist with any information I will greatly appreciate it. Thank u Amal (mom)