2002 ford escape v6

I got a call about a family member
needing emergency help so I step
on gas to go around other cars to
get there. The next day my oil light
was flashing, just thought it
needed oil change, got oil changed
and later that day as I was pulling
in parking lot I hear a loud rattle
like noise from engine and vehicle
cuts off. I started it back to move
out the way, same loud noise, get
a parking spot it cut back off. I
didn't start it back up bc didn't
want to cause anymore damage. I
took the cover off where the coils
are bc that is where the noise is
coming from. I started back for a
sec. To see. It coming from behind
the coils and it is like something is
loose, you can put your hand on
the cover and feel it hitting. Could
it be a rocker? Could I fix it myself?
Can't really afford a mechani........