DS went through something like this around your DS' age. It started with the night sleeps, then one day sleep after another was affected. He also became very clingy & would cry at the drop of a hat! It was stressful at the time so I can relate. I'm sure it's not easy having your DH away too.
In our case DS just snapped out of it. Just when I thought I couldn't take any more he suddenly changed & started sleeping better! I think he was going through a developmental stage as I heard of other bubs around his age doing the same things.