Really nervous about doctor visit

Really worried about my health based on doctor visit [Question - other]

15Male
5’4 
98 lbs
Non smoker

went to the doctor for a Covid test since I’m going back to school soon. I don’t have any symptoms really maybe except a stuffy nose but I didn’t realize until somebody pointed out to me that I was sniffing a lot. 

I got the typical tests done. Nose check. Mouth check. Breathing check.

She said my chest felt very congested. She didn’t seem concerned but she said it could be Covid or some other virus. Idk what she meant by congested. 

I sometimes get tightness in my chest randomly (mild pain) but it goes away. I’ve never had any extreme pain or anything.

But I’m really worried that something is serieouyl wrong with me.