From LVL 73 to 72 ?

I was yesterday on LoL and i go lvl 73 and today i just open LoL client and i have lvl 72 with 0 xp IDK wat happend but i think its cause of the update to 8.5 if you think i am lieing then ok but i rly want dat lvl back cause its hard to get lvl 100 if i get somthing i call LVL BACK