My Son Is 2 1/2 Years Old. He Has Been

My son is 2 1/2 years old. he has been battling colds for the last year every two to three months. His primary believes he has asthma underlying. He has been treated for Croup and Upper Respiratory Infections multiple times. approximately3 weeks ago, she switched him over to Pulmicort twice daily to control his asthma and hopefully decrease this episodes. As well, to decrease the amount of orapred (steroid use). Since then, he has had two episodes of the croupy cough that then settles in his chest. Yesterday, he started getting the barky cough around 5 pm. When giving him a bath last evening, he has a bright red rash on his upper buttocks/low back that wraps around his waist. We were up all night with him as he was crying and coughing. I gave him his prednisone at this time. He was also very warm at that time, gave him Tylenol. We continued through the night, alternating between Tylenol and Ibuprofen. Today, gave him his second dose of prednisone. He has been running a low grade fever all day, continues to have the barky cough, and rash is also still bright red. I am lost at what to do....