Sleep through the night!!!

So Thomas was finally sleeping through the night. (For about 2 weeks now) But for the last 2 nights he has been up all dang night. I find myself rocking him at night praying that he will just let me lay him down and then when I do lay him down he starts screaming. So I bring him into bed with us but he won't sleep with us he plays and squirms and crys. So I end up in the front room watching infomercials holding my 22 lbs son on my chest and rocking. Heaven forbid I stop rocking him because then he just starts to cry again. Shouldn't he be sleeping through the night! He is almost 8 months old for goodness sakes! Well he just feel asleep for a nap so I am going to lay down to try to catch a few winks.