You’ve already gotten lots of great advice above. Best of luck to you and your son.
I work at a university and I wanted to make sure it was clear to you that the school is not going to want to refund your tuition and will probably not be flexible about this. (If you get money back depends on if you have tuition insurance and their guidelines.) On the other hand, universities have a lot more flexibility with granting medical withdrawals. Withdrawing from all his classing will be probably be much better than receiving D’s and Fs, so you ask for this to happen ASAP. Many colleges will grant this with any type of doctor’s note, as they don’t want to deal with the liability around mental health issues if they say “no.”