Hi there!
You'll join many with your same issue, after a major update. I would recommend entering recovery mode and Wiping the Cache Partition....see if that helps...if not, then I'm afraid your only other option is a full factory reset. Personally, I do a full reset after each update, but that's just me.
IF YOU DO THE FULL RESET.....BE SURE TO BACK UP YOUR PERSONAL DATA, IT WILL ERASE YOUR PHONE TO STOCK.
Hope this helps!
Chris