I Live In Cedar Rapids Iowa And Have Been Having

I live in Cedar Rapids Iowa and have been having a lot of breathing problems for over the past week and a half. It feels like someone is standing on my chest and sitting or laying down makes no difference. I haven't been doing much, but resting. It has gotten progressively worse and I was blaming it on the heat and humidity lately. I walk my dog for short walks when its hot and then wait till almost sundown and then we walk about a mile and a half, maybe longer. I don't hurry, we take our time and enjoy. The last two days it is worse and I've been having headaches also, just dull ones. I have had the air on in my apartment, but it's set at 73. Today I had to go on the city bus to get a few groceries, went for dog walk and back. Headache again, and now I get hot and then cold. Don't have a thermometer, so I don't know what my temperature is. No sweating, but is very hard to breathe. Not sure if I should go to the hospitals ER or wait it out. Please give me your opinion
Thank You