What is my true problem?! Head gasket or heater core?

For background, I was traveling back from Vegas when I realized that I could faintly smell coolant coming from the A/C. It was a very faint scent though. However, at the time, I was 20 hours from home... Fast forward 7 weeks and the coolant smell has not dissipated.

About 3 weeks ago, I noticed a small puddle of odorless water right where my right foot rests as I drive and it has continuously gotten a little bigger.

2 weeks ago, I was in a drive-through and noticed that my A/C got hot. I checked the engine temp and the gauge was 3/4 high. I pulled over, turned the engine off, and checked the coolant--It was dry. I put coolant back in, waited for the engine to cool, and drove home. The next day, the car tried to run hot again while waiting for a red light to change. Again, I pulled over and checked my coolant--It was full. So at this point I am extremely confused. However, the car never ran hot again.

I took the car to my dealer so that they could diagnose it. ****(At this point, my car is 500 miles from the warranty running out)**** They told me that the issue was a resistor that prevented my radiator fan from switching on to hi-speed. They told me that they would order the part and contact me as soon as it came in... Well they never contacted me. I called and they said they part had arrived 4 days ago. I scheduled another appointment to get the car fixed and went on about my business.

Yesterday, hell broke loose.
I drove the car 1.5 hours straight--no problems. I get to my destination--everything is fine. I drive around town a little--no issues. I continue to drive and my engine temp jumps up to 3/4. I pulled over, checked the coolant, the level was fine. Waited for it to cool and began to drive again. I drove for 30 seconds and the same exact thing happened. At this point, my goal is to get the car to a safe parking lot, so that's what I did. On the way, my temp gauge stayed at 3/4.

I had my car towed to the nearest dealer but all service departments were closed, of course. Meanwhile, I am stranded. So my only option was to cautiously drive the car back home. So that's what I did.

All the way back home, my temperature gauge was having a field day but never went higher than 2 notches to topping out. Also, the puddle around my foot continued to get wetter. Since then, I have had the car parked. But my insurance will not give me a car, nor will my dealership, and I still have to get to work and summer school.

Can someone please give me an idea as to what is going on!? I take absolute care of my car. This is the very 1st issue it has had and I am just beyond frustrated and confused because I spend money on maintaining my car before anything else.

The car has 101k miles.

Thank you in advance.