My daughter has always been a great sleeper, but she still does wake up from time to time in the night. My method of dealing with it was always to respond quickly... the sooner she knew I was there, the more quickly she'd fall back to sleep. Like adults, kids can wake up for no reason in the night and for them, that's scary when it's mostly dark and they're tired and can't see anyone near them.
Have you talked with him about it, asked him if his ears hurt at night or why he get's sad? Sometimes giving my daughter another way of "getting my attention" is all it takes for her. (I.e., If you wake up at night and want mommy, all you need to do is call for me - I can hear you and there's no reason to cry and feel sad - it makes mommy sad when you cry.")
Another thought might be to buy a noise activiated musical aparatus, like the ones they have for a baby's crib - if you think music might loll him back to sleep.
It's frustrating when we can't get enough sleep, but I'd remind your husband that he's still mostly a baby and that he'll outgrow this phase, to please be more patient with him.
Best of luck!