The antibiotics they are giving you for the mastitis are probably clearing up the sore throat bug. Hot water showers, warm cloths on the area, nd gentle massage will help with milk flow. Once the milk flows freely, and the antibiotics kick in, the mastitis will clear up. I had it with DS1. Horrible.
I would too. Something must be happening to cause the behavior. And since it happens in the classroom I would want to watch a class to see ehat is happening and how the teacher is acting.
I think probably something happening in the first preschool that was causing the problems. Separation anxiety is a symptom of problems. Of course, it can also be a sympton of a type of LD. DS3 had terrible separation anxiety in kindergarten. It eased up when we ran a carpool with one of his friends' parents. However, later in school he had trouble spelling. Turned out he couldn't remember the letters the sounds went to. He learned to read fine since he could identify the sounds when he saw the letters. He also never drew anything because he couldn't recall what the object would look like if he couldn't see it. We realized that the separation anxiety fit with that LD condition since once I was gone he couldn't remember my face. I gave him a photo and it helped. He eventually outgrew a lot of the problems. Never did learn to spell properly though.
Hopefully the new preschool will be successful. How old is he?