STM and attention span are weak af?

This has been going on for at least 5 months now. I've noticed that my short-term memory is very bad now and my attention span is shot. With my STM, 8 times out of 10 i can't remember what I was just told, what I just said, or what just happened in the last 3-10 seconds. If I was told to do something I'd forget about it in 5 seconds. My attention span is just broken. I get distracted and knocked off focus so easily. I was playing some csgo earlier and as I was waiting for the enemy, I dozed off after around 10 seconds of quietness and nearly got killed. Even when I try to focus on studying or homework, I can't stay on task for more than a few minutes. My mind is always coming up with random stuff for me to focus on or maybe I see something and decide to take a quick look at it. Every time this happens, one thing leads to another and I never get back to what I was originally doing. In school, I find myself constantly moving, thinking, looking around, finding something to say to friends when I know I should be focusing on the teacher. If I try to hold an idea or something in my mind, it slowly fades away by the second. I do my best with this but I'm still failing. Any help?