J.O.
Don't worry, it's completely normal. Both my daughters have done the same thing, around the same time. I even have a couple of friends who have complained of the same thing. If nothing helps to calm him, than do nothing. I know that sounds harsh or mean, but I found the more I tried the more aggrevated they got. I would just sit him down somewhere quiet, but close enough to you that he feels safe, and let him cry it out. You'll be there if he starts crying for any reason other than waking up... and it will teach him to work through these things on his own. I hope this helps; this can be very stressful.