My 5 month sold son cries now when not held and refuses his pacifier, do I let him cry it out in his crib?

Here is one thing I've learned as a mom. EVERYTHING is a phase. The sleeping, the eating, the moods, everything. He might be going through a growth spurt (6 months is when a big growth spurt hits), he might be starting to get teeth, he might have learned something new like rolling over, and whenever they learn something new you can expect changes in sleep or eating or moods. I understand about being completely exhausted, I have two boys who are now 4 and 8. My advice to you is do whatever you have to do to get yourself the most rest. At 5.5 months you are not going to spoil him. Don't follow someone else's ideal of how he should be acting, follow his lead. If he's crying, he wants to be held. Of course it's up to you if you pick him up or not, but if you decide to let him cry for a bit (which, if he's not over the top crying, is a perfectly acceptable thing to do) then be prepared to be stressed out while you listen to him cry. He's only going to be little like this for the blink of an eye and then he'll be big. I remember how frustrating those nights and days can be when they won't even let you sit down and rock them without crying, they want to be walked around. But hang in there, it will end. I promise.