Playgroup - does your child falls sick often? Need your opinions and suggestions please.

My 18M old daughter started childcare about 3 weeks ago. She's been falling sick often - low grade fever, high fever, runny nose, coughing. We've been to the Dr twice. Just last week Dr prescribe antibiotics cause of prolong cough. Mummies can share your experience please. I'm so anxious now. I don't like it when she falls sick. So poor thing to look at. She's a lot better now but have low grade fever here and there. Does your child falls sick often? Will the always have runny nose? I see the other kids also, always have runny nose. Coughing.. how long will does your child take to recover? My daughter is taking vitamins. Is there anything that you give to build up their immunity? Thank you! FT mom here, anxious about a lot of things.