Clicking behind engine 2001 ford focus?

My focus has 111,000 miles on it. A week ago it started making a ticking noise. It sounds like it is coming from behind the engine. It doesn't sound like the valves but it is not all the time. Sometimes its louder and faster and sometimes its not at all. The other day it started a new thing. The temperature goes up and when the fan comes on the car shakes horribly. It feels like it is going to stall but does not. Any ideas what's wrong with it?

Dropped valve seat common on those engines. Its misfiring on the cylinder with the dropped valve seat.

Replace the nuclear reactors.

Clutch

It sounds like you timing belt.