Well it could be asthma, I know when my asthma starts to act up, my chest gets tight and it is harder to breath. I get foggy until I take my medicine or do breathing exercises. Don't get up so fast, try breathing in through your nose and out through your mouth for five minutes. If it helps you may be experiencing asthma. It could be from seasonal changes. Either way you should make an appointment to see what is up for sure.
Have your gas lines in your house checked immediately. Set up a carbon monoxide detector, as well. The only other guess is that you have mold growing in your house. And get some medical attention whether this is these problems are the case or not. You owe it to yourself to stay healthy.