It sounds like he's a pretty scared little guy!

If you can, give him a place that's just his to sleep in. Maybe a carrier. If you can confine him to a room with a baby gate for a few days it might help. He needs to feel secure before he can interact with the rest of the household. The baby gate will let him smell and see everyone else, but protect them from him (and vice versa).

Eventually he should be able to understand that no one is out to get him. Introduce him to one of your dogs at a time; don't rush it.

Let us know how you do. It could take several weeks or more.

Mary