Your son just hasn't learned to self soothe. This is apparantly very very common. We went through this as well when my little guy was about 8 months.
We did most of what Athena talks about, and it did work. However, prior to starting that portion of it, we slowly weaned him from night feedings. So with every night feeding, we slowly decreased the amount he got. He would still be awake, and we made sure to put him down that way. Then, when he wakes up, he is comfortable with where he is. It has to be scary for him to fall asleep in one place and wake in another. Once we had him weaned from night feedings, we started what Athena talks about. Instead of picking him up from his crib I sat beside it, stroking his back and talking soothingly to him. A few weeks later he was sleeping through the night.
A really great book on this subject is "Healthy Sleep Habits, Happy Baby". My Pediatrician recommended it, and it worked. It's based on much of what we have posted.
Good luck to you, I know how hard sleep issues are. But they can learn to self soothe, and when that happens everyone will sleep better and be happier.
I feel your pain. My baby is not sleeping through the night either. I am unable to nurse, but she is very attached to me.
My doctor said to only let the baby cry for 5 minutes and then go get the baby. Also the doctor said to let the baby get used to the crib during the day put some toys in there and do the 5 minute rule. Do that for a week then try 10 minutes of crying.
Also give your baby the shirt you wore that day (of course make sure it a safe item of clothing) so your son smells your scent.
There is a heartbeat teddy bear that is supposed to help babies fall asleep. Maybe try that.