Feeling upset for no reason

Nothing has happened has happened really. I played PlayStation with my friend and he was kind of being snappy with me. He was shouting at me about the game a lot and some other stuff because we were having issues getting connected up. He also admitted to saying stuff about me behind my back to another friend. That's it though, all it is was my friend was being snappy and then after we have finished playing PlayStation I go in my room sit on my bed then I just feel down but I don't know what. Its not because of my mate. It has been a stressful time for a lot of us but I was feeling fine before I was down then I just feel down and I have been feeling like this the whole day. Im not fully sure why I'm feeling like this. I have had a few issues with my self confidence because I have not reached certain milestones that I have wanted and the whole pandemic has stopped me from doing certain stuff.