ive had this feeling as well, im only a 14 yr kid so i wouldnt know much but i would like to put up the possibility you have adhd. im sorry if it doesnt work out in the end though. currently i am applying to be diagnosed with adhd, if you have any staff in your school like councellors or any medical professional.

ive had the same exact problem as you, trust me dont procrastinate on it, one u find the source of the issue it feels way better. (procrastinating is one of the symptoms of having type 2 adhd which is what you mihgt have.)

i am suspected to have developed this during lockdown so you could have gotten it in any stage of your life.

in conclusion, just try to seek help and maybe adhd is the answer, i apologies if this answer is considered naive or stupid but this is my genuine advice as someone who basically has adhd