This past year, a number of students have had a very hard time, socially, at their schools so, he is not alone. For now, he needs to go to the counseling center to talk to someone because he needs support to get through the year. He needs to understand that this is very common now.
As for transfer, each school has different requirements for transfer. The UCs accept Junior transfers, as noted above. Private schools have different requirements that you need to check. Good luck!