Maybe you could ask him what`s going on.
And if he tells you and you regret what you did (if you did something), you can apologise and try to fix it if possible.
There is also the chance he doesn`t forgive you. If that is the case, dont try too hard to gain his forgiveness, but dont seek conflict with him and let your actions show that you grew out of that 8th grade phase. Dont start new drama (i think you are more mature and overcame that drama phase, but i am still telling this just in case)
Even if he doesnt forgive you, forgive yourself but make sure you do better next time and make sure you are becomming a better person.
Hope this helps and wish you the best.