Just venting and needing advice

I'm a secondary student and i need advice for my problem. I don't know why or how to explain but 2022 wasnt much of a best year for me because lately im slowly changing badly, I often dont do well in work assignments or homework, i struggle to study and a very slow learner and all of that..sometimes im absent for a week the longest, i do have my reasons but teachers of course need the evidence like a doctors note and all. Once my homeroom teacher called my mom saying if i keep this up i will get a warning, so of course my mother was upset and threaten me to not have excuses and all so i started feeling bitter and shameful about it.. Everyone has those intrusive thoughts right, sometimes all my thoughts were just about "why can't you do better" "why do you act like this" "I dont feel the will to live much longer" or "I'm just a disappointment" yk those. Well after awhile i got better until last week, i got sick like a fever.. we didnt go to the clinic yet until the next day and yep, another week i was absent. I felt really bad about it but i was afraid to go back to school but i had to and it was today, i was all well prepared i did had a bicker with my mother but yeah i waited for the bus and an hour or so the bus didnt picked me up then k realize i didnt tell him i was not absent. Of course i made a decision to call my mom and she was not happy and either is my dad i understand why but i felt like a knife went through me and my teacher called why i was absent i told her, she told me to tell my mom to call her(the teacher) and if i dont tell her she'll likely expel me from the school. I dont wanna get expelled but im also scared now i dont understand why am like this at all. my parents are usually home around night and they'll just nag to me about this and yeah i know im in the wrong so please give me advice on how to improve or change myself for the better.
Also, hope whoever read this had a nice day bye<3