Periodic fever, cough, cold, vomiting.

My 3 yr old daughter gets fever, cold, cough, vomiting and sore throat...once evey 30-45 days (irrespective of the weather or season), and this has been happening since over a year. The fever generally lasts for 3 days. The cough takes about a week. The vomiting is especially difficult, even ejects the medicines along with whatever she eats. We've consulted multiple pediatricians. One diagnoses it as viral fever (every time) and prescribes the usual paracetamol, cough and vomiting medicines. Another one prescribed a urine test to check for infections, but that came out normal. He said that if the fever isn't going over 4 days, there's nothing to worry. We also tried homeopathy, and it seemed effective for 1-2 months, but this time, it doesn't seem to work.