New update seemed to hurt my battery life, anyone else?

My IPhone 6s Plus just updated to the most recent OS and it has caused nothing but problems. To start the phone will randomly restart itself and when it turns back on it always is at 10% battery. Within three minutes it will restart itself again and go back to the battery % it was at before. Now this doesn't happen just once, no it happened to me last night at least 7 times within 3-4 hours. And today it has continued doing this and has done that restart cycle around 5 times today. The only way I have found to prevent this is to constantly have it plugged in or keep it above 80% or it will restart itself. On top of this the battery life has gone to crap. When the phone doesn't restart the battery will just tank. In a 10 minute drive to school having Spotify running in the background, the phone will loose at least 30% battery.