Help extreme mood swings help help HELP!?

okay im 12 and i have rapid moodsings.i can feel on top of the world one moment and then the most stubborn meanest irritable person in the whole entire world.i really dont mean to be like this and my 1 best friend can obviously tell and i cant blame her.somtimes im my bubbly self and i talk fast and obsessivly while im very happy then 1 second later im completley ticked off.i often get extremley mad when people correct me or tell me what to do or if a feel any vibe of favoritism.i often suffer bad emotions too.somtimes ill cry for not much eason at all.i even feel extremley sad and ashamed every time i do somthing right or i get the best grade in my cl.i often become snappy irritably stubborn and grouchy and have a o toleranc rate.i really dont want to be like this,it really makes me feel ashamed after one of my moodswings or even my HORRIBLE tantrums i throw often.do i have some type of disorder?is there any way i can fix this or cope with all my emotions.i also have adhd but i really dont think tht has much to do with it.HELP im becoming a monster!!!!!!!!!!!!!!!!!!!