presyncope i think

ive had a lot of near fainting experiences but all of them were at school except todays.. ok so basically ive been laying down for 3 hours straight and i finally got up to shower right, i felt fine for the first 5 minutes of me sitting down on the toilet thinking ok should i shower or not?? and then i felt this insane lightheaded feeling and then i felt nauseous and then i couldnt see and htne i couldnt hear so i grabbed all my things really clumsily and ran to my room and started laying down again because since ive had these experiences before i know what to do.. i think? but anyway for the next 30 seconds all i could hear was this buzzing noise at the back of my head which i absolutely hated. the entire experience was just like when you sit down for too long and stand up and you feel dizzy but like 5x worse. i wouldnt say 10x worse cause its not that bad i guess