He literally won't speak to me

He is a narcissist or something else.
I've come to the conclusion that men are just stupid in relationships.
Or perhaps he is bipolar and you need to read up and ask him to be honest about his mood swings.
Perhaps pregnancy has left him feeling second best. If that's the case he's got real friggen issues . Good luck. And remember, lotsa women raise their children alone. Regardless...do you want this man to be an influence in your child life. You may have made a bad choice... Teach them that women deserve respect. Or have them grow up to be like mine. You choose.

Out of 50 people your the only one to respond. Thank you!

He's got issues. His means of dealing with discomfort (physical or emotional) is to clam up like a child.

You need couples counseling. He needs to learn a means of arguing and getting his points across without either putting you down or shutting himself down more or less completely. You need to learn how to draw him out - or how to let his crap wash off you.

If he won't go, go alone. And, you should understand, couples counseling does not necessarily mean there is a push for you to stay together. It is a means of learning to communicate more effectively.

Is this something new - or is this how he reacts to most things? Is he pouting about something? What does he think about the pregnancy?

You don't mention his work or health. Are those issues?

Yes,, couples counseling is warranted.

Never go to couples therapy if your agenda is to change your spouse. Especially if you have to beg or manipulate them.
Ask him if he sees there is a problem, give a few examples. If he agrees there is a problem ask him if he will go tp a therapist to learn new communication skills. If you have a daughter he adores, ask him how he would want her future husband to treat her. Im sure his answer will be better than he treats you. So why are you not worthy of the same.
Tell him in our stupid society no one knows how to communicate with their spouse any more.
If he goes great. If he wont....get out. And don't be bull$hitted back in.

This is not new.. It happens Every other week / every couple weeks. There is normally nothing that provokes it. The other night we we talking and watching TV like normal and then his mood just shifts. I can tell. I asked him what was wrong and he said I'm tired and my back hurts . I said OK and didn't push him about it anymore. 30 minutes later he says I'm going to go to bed take care of the dogs . I said OK thinking he was just tired and will be fine in the morning. But the attitude continued in the AM and all through out the day he was distant and cold and it hasn't stopped. And I know he talkes to people at work or his friends like everything is fine but when it comes to me he is cold. After a couple days he will go back to normal. We both were shocked about this pregancy because it is so close to our daughters but its a boy and he is thrilled now. But I don't understand why he becomes distant out of the blue.

If he is not bi polar or borderline personality perhaps he is screwing around.
Goes back and forth with his guilt etc. Perhaps he is struggling with something else sexual. If he likes having sex with you remind him that you actually have to "want" to have sex with him and his attitude is taking the wind right out of your sails. This phrase really woke my husband up...as if he could treat me like a common citizen and then expect me to just give it to him because I'm his wife.
I personally am not against a little snooping if there is real cause for suspicion. Most people will think that is just awful advice, I don't give a crap.
The more I read this forum the more I see wives like myself are struggling with husbands who have a sense of entitlement, expect wives to put up with everything and expect nothing less than a whore, babysitter, house wive, Stepford wife with a smile on here face who keeps her mouth shut.
The more I assert myself in this marriage the more my husband is convinced I have issues that need medication. There was a time I was on Prozac after the birth of my second son. My husband really liked the fact that I complained about nothing. I recently read an article in Oprah magazine about being medicated to the point of being overly compliant.

I know people who are rude to others because they are in physical pain.

Pain is a distraction and it takes immense energy to get thru the day. His irritability at home may be because he can finally relax - and then he is asked to be an attentive, participating spouse. Too much for him!!

Get this back thing looked at and solved. He should not be in such pain.

that sounds very sad and depressing honestly!
I had a boyfriend like that, when he would get mad he would not say a single word for hours, and hours. What I did best, was ignored him once he got past this annoying quiet phase.
Have you tried talking to him about this?