1997 Ford Escort Weird resistance while car is in motion.

I left the store a couple weeks ago and I all of a sudden heard and felt something that wasnt normal
I immediatly turned around and parked, and looked underneath and I think I saw oil all over.
The car while in motion was making a resisting knock, it seems like every rotation or something like that
the faster the car moves, the faster the knocking, at a uniform rate

I could be in the car not moving and rev to the limit and not feel one thing wrong
but if the car moves it makes the noise and resistance.

Even if the engine is off and the cars in neutral, it still does it
and idea?