if I am reading this right, he was fine during the play dates and transition period, but isn't ok today.
He might be teething, or coming down with a cold.

Also I can't even get any of the kids dressed to go outside or go to the bathroom because he will just scream and cry if he doesnt see me.
it will not hurt him to cry well you do these things. Don't let him stop you form going outside, the fresh air might do him good. If you have to go to the bath room go, don't damage your bladder because of him.

my own son has done this to me. I will hold him for a while, but them I will put him down and let him cry.