Toget help and explanation ofthis problm

Hello doctor, I don't know what's causing my hair to fall last time you did'nt let me explain well enough, back when I was 16 years my hair was perfect in every way everything was well balanced but it just changes suddenly when i attained 17 years now it just went the opposite ,3years ago my hair was straight soft and smooth but now it's curly dry ,back then my hair was thick and volumes but now it's not like that anymore I don't know why. Last time you told me to do that test, do you think it's necessary for me,and dandruff also is starting to go away but my hair is still falling and it has a big white bulb at the end of the root it's yellow in colour and and also the thickness of a strand is not uniform, sometimes are normal and some are so thick you can the difference between them,and also my side hair were not so spiky like this before it just changes in that age gap please provide me with a clear explanation what to do and what not to do? I need your help