iOS 8.3 12f70 bugged upgrade

i recently upgraded the firmware of my iPhone 5s 64gb to the latest Apple firmware 8.3 12f70 about a week ago and the last couple of days have been experiencing some issues. I first started noticing problems with apps crashing unexpectedly and minor overheating along with storage full notifications (Even though on my last backup/update I had 11gb of free space. I have deleted some larger apps and a movie from my phone to free up space. I then continued to receive the storage full notifications regardless. Since, my mail has not been able to open for longer than 2 minutes and after the first crash that time of usage is quickly reduced eveventualy to an instant crash, whilst a message in the mail settings States that mail is syncing to the server even though it is not set to back up to the cloud?? Messages are not sending and receiving through I message or text properly and only pushing through shortly after I reset all the settings. This seems to be progressively getting worse. Along with this I am also receiving a flickering screen and phone getting locked onto airplane mode and dropping service. Has this happened to anyone else? I am looking to restore from a backup later when I am at home, however this seems like if it is the firmware this will just happen again? Suggestions?