A child with a cold and fever has appeared bleeding spots on the face and neck. What is it?

Patient's question:

Patient gender: nv
Detailed condition and consultation purpose: Child with a cold and fever of 39 degrees, with petechiae appearing on the face and neck. Why?
Duration of this illness: One day
Current general condition: Body temperature has returned to normal after intravenous infusion, but the petechiae have not disappeared yet
History of previous diagnoses and treatments, as well as their effectiveness:
Medical history:
None
Auxiliary tests:
Other:

Doctor's answer:

Check the blood routine to see if the platelets are low. If not, you should go to the hospital to check if it's bleeding spots or rash.