Having a hard time coping in the third trimester?

I'm 36 weeks and ever since last week I've started having a really hard time coping with everything going on.. I'm in pain more than I'm comfortable, I can't sleep because of it and I just feel a little depressed. I'm a HAPPY person by nature and I'm sitting here at 4am crying hysterically. I'm just at a loss and seriously don't know what to do...... Anyone else go through a small period like this?