Hello Lynne,
It sounds like your battery could be going out, if you have had it for about a year and a half or so this would be right on schedule for it crap out.
However before going about replacing the battery I would back up all your information to your sd card. I use mybackup free should work for your case or upgrade to pro to access the info from other devices or use cloud storage. Then go into settings and find the reset tab and factory reset your device then load your back up and see if that helps! If it doesn't I can help you further with the battery replacement!
Hope this helps!
:if you find this helpful please vote up the answer to aide to my rep, I will do the same!
Thanks Lynne!