R.D.
It is obvious that this hasn't been done prior to this. After his dinner, give him his bath. Let him play a little and spend time with you and yours'. You didn't mention so I thought I'd be polite. I would have him in bed no later than 7pm. if he cries, he cries. If it doesn't stop, go in check his diaper, take him a drink and away you go again. Don't give in, even though they are young they catch on quickly. This crying may go on for about 4days but at least, for your peace of mind it will work.. Let him cry it out. Don't run right for him, thats a no no!! Just a drink, check diapere, if all appears normal, then leave the room and listen. I am not a professional person only someone who is in the Healthcare field. You can't cry when he cries, he will get over it, and it will never be spoken about again. They forget quite quickly.
Good luck and I wish you the best.