My back aches, I'm congested, I'm gagging but nothing is coming up..I go from being hot to having…

My back aches, I'm congested, I'm gagging but nothing is coming up..I go from being hot to having the chills. What could this be pregnancy symptoms, allergies, or covid!? My Sister just told Me I sound like crap and I have covid. How could I have covid when I wear My mask, constantly sanitize My hands and last week I didn't have a fever and I stay inside most of the time. I got this congestion over night. I'm really starting to worry because I don't have a fever just blood pressure is a little high right now.