My Chevy Tahoe started blowing white smoke from the tailpipe. What could be some of the reasons it's doing this.

Danielle, Hesitation and white smoke could be a sign that coolant is leaking into engine cylinders and causing plugs to fowl possible head gasket faulty.. Have a good Technician have a look, diagnose and estimate repair.
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White smoke out of the exhaust indicates moisture (water) in the exhaust. If the car is not driven very far each day, some moisture will collect in the muffler and cause white smoke for a short while after starting. If the smoke is continual, however, you need to watch you coolant level as you may have a blown head gasket.

It sounds like a head gasket problem to me

could be 2 reasons.
1. start of a head gasket leak to the combustion chamber. Will become more white and for longer period as it gets worse.
2. oil rings are worn and starting to pass oil to combustion chamber. They seal up once engine is worn.

if white smoke is blowin out the tailpipe its a blown headgasket

white steam or smoke from tailpipe is a bad head gasket and or cracked cylinder head.

The white smoke is probably steam caused by coolant getting into the cylinder(s) either from a faulty head gasket, cracked cylinder head or cracked engine block. The loss of heat from the heater indicated that coolant was being lost..

Whatever you do, do NOT continue driving it this way until it is fixed. Hydraulic lockup can bend a piston rod ot even detonate the engne.
I think it got so hot at one point that it blew a head gasket.
Have a qualified mechanic perform a cooling system Pressure check.
If it holds pressure, which I doubt, it may be antifreeze running into your cylinders from he intake manifold. But the pressure test should tell you which head gasket it is, but have BOTH replaced, since they both underwent the stress.AND while replacing those gaskets, a new intake gasket will be installed too, as a matter of course. The price is about the same, since they have the top of the engine apart anyway. Just for information: White "smoke" is vaporized coolant or water being pushed out the tailpipe from the engine. Blue "Smoke" is oil, and Black "smoke" is soot- too much unburned fuel.

The smoke you are seeing is most likely oil seeping through the valve stem seals into the combustion chamber .......

You have a blown head gasket. Get it fixed ASAP before you ruin the engine.