What Causes Tonsillitis, Fever, UTI And Bronchitis In A Child?

Seeking a pediatrician. My schhol: daughter just called very worried about her little girl. She started pre_school.age 2.5 yrs. Started off with tonsillitis. High temp.Then UTI. Then bronchitis. Then the croup and had to go to hospital and get breathing sessions. Then canker sores in mouth _ not thrush. Temp is in flux now 102. All back to back and overlapping. Autoimmune? Flu? Pneumonia? Very fatigued. What type of blood test would you recommend?