NHTSA Complaint #11557207 — 2016 CHEVROLET COLORADO

I have asthma and it is controlled by medication when needed. Recently I have had a lot more incidents of breathing difficulty since I purchased my vehicle. It was during one of these episodes that my wife noticed an odor associated with antifreeze. However, there is no moisture in the vehicle and no visible leaks or puddles on the ground. I have detected the same odor when standing near the back of the truck near the tailpipe. Also, I have had to refill the radiator with exactly five gallons of Antifreeze in less than 3000 miles of driving. It was my wife who alerted me to the odor being inside the vehicle and only during times when the heater was running. Since that time I have driven the vehicle only when I can safely leave the heater off, because I cannot be sure it is safe. If I need the heater to defrost, I leave the vehicle. Also, I noticed that when the engine coolant is low, the engine never seems to overheat, and the heater no longer blows hot air. Is this an issue involving only my vehicles and what other health risks are there? The most I have had to add to restore heat is a gallon of coolant.