My toddler is always sick

So my daughter is into week 4 with a bad cold. It started off as a runny bug and fever then went to a cough. We thought she was finally getting better last week but the. Yesterday morning she woke up with a high fever and coughed until she threw up. I took her into emerg and they gave her fluids thru and IV as her temp was so high and heart rate was at 197, they also ran a chest X-ray but that came out clear. After 6 hours they discharged us with an inhaler and said to give her that for 10 days and Tylenol every 6 hours.

I feel like she is never going to get better. Has anyone else had the same experience where their child is constantly sick. Im really worried. They ran blood work too and all came back good.