Hi. I Have A 5yr Old Son. He Had A

Hi. I have a 5yr old son. He had a fever of 104 for about 2 days. And a bit of a cough that sounded like a seal. I assumed it was croup since he had been around someone who had it. However, the symptoms, other than the seal cough, were not the same. We're 7 days into this he still has a bit of a cough and now as of yesterday, he has a bumpy rash from his under arms down to just below his rib cage and on his inner thighs. What could this be? I looked rosella but that doesn't seem to fit the symptoms either.