What Causes Frequent Recurrence Of Throat Infection?

My daughter (33 months) has been suffering from throat infection for the past 3-4 months. She starts with cold every Friday, gets well by Wed, then goes to school Thurs and Friday and falls ill once she is back. We often need to nebulize her. She is currently on Levolin syrup and Matrix syrup. Last night i noticed her jerking and twitching in her sleep. Not violent, slight jerks. She was an early talker and walker and did not have such jerksin the past. But last year as well, she started falling ill around September, which lasted all through winter. This year is worse, since she is almost ill every day (except Thur and Friday per week.) Please help.