Coolant leak/gasket repair

I saw a fluid building up under the floor on the passenger side. Upon closer inspection, saw a slight green tint to the liquid on the floor. Looked under the car and saw a constant drip. Opened the hood saw my radiator reservoir was really low. When I opened the coolant reservoir cap, the drip under the car began to drip more rapidly and would slow down once the cap was tightened back on.

Car never overheated and no white smoke ever came from the exhaust pipes.

Manually checked the radiator hoses. They are tight and no leaking coming from the hoses. Got under the car to look for the leak and saw it dripping on the outside of the engine. Cannot find the exact place where it is leaking from with out taking anything apart.

Started the car to back out the drive way and heard a squealing. Sounded like it was my belts. The squealing only occurred when I backed up or was at idle at a stop sign. This is brand new, never heard this before.

Again, no panel lights come on, heating gauge is normal, and no over heating is occurring.

Drove it to Pep Boys, they said upon quick inspection. Taking off my oil cap, they saw milky sludge on the cap. They believe my head gasket blew. And might have internal and external leaking.

Drove it a few blocks back home, and the squealing is now more prominent when idling at a stop sign. After parking it, more leaking occurred under the car on the right passenger side of the vehicle.

The coolant reservoir is now more empty.

When searching for possible causes, I never experienced my car over heating, no white smoke, nothing on the gauges to tell me otherwise. It happened suddenly.

If it is my head gaskets, does this mean I should have seen white exhaust and over heating or can a head gasket blow w/o overheating etc.

What are signs that it could be a water pump issue?