The first thing you should do is get your custody case removed from the current judge. He has an obvious conflict of interest because he is friends with people on the dad's side. Hasn't your lawyer advised you on this? Your lawyer should be able to get the case transferred.
With respect to the day care, you can do several things:
-Call the director of the day care and ask how your son is adjusting. The director might be able to tell you some things that your son won't tell you.
-Tell the pediatrician about how your son is getting sick now that he is going to the day care. The doctor may be able to make a medical recommendation to pull him out of the day care, which you could use in court. At least you are going on record with the doctor about your son's health, so if the medical records are ever entered in court, they could help show that the dad is making your son do an activity that is harmful to his health.
-Introduce yourself to some of the other parents that send their kids to the day care and ask them if they are having a similar experience.