What are the disadvantages of geothermal energy only?

We just had a Geothermal system put in. All was fine, but after about three or four days, my wife and I started feeling sick.

I was lifgt-headed. My wife was more sensitive and had headaches, burping, nausia, upset stomach, and burning eyes.

The technicians were out but couldn't find anything wrong.

We have it off most the time and is frustrating with high tempurtures and humidity.

We had the ductwork cleaned, vacuum serveral times and dusted to no avail. Everytime we put it back on the symptoms come back mildly in a few hours, then worst in about a day.

The company isn't very cooperative, and it's very frustrating. Never imagined having these problems.

If we can't fix this fixed then what do we do? Install another regular furnace and air condictoner?