sms/text messaging keyboard causes phone to crash

Hello. Since updating to ios 9.3/9.3.1 I am constantly having an issue with the keyboard and phone perfiormance during text messaging only. There are two problems which are very annoying. The first is sometimes the keyboard will disappear while typing...now that I think about it, this has happened during email too. I then have to close the app and restart the phone to resolve. The second, which is a greater problem, is that the phone will completely crash while typing during texting and the phone will crash if I receive multiple texts almost simultaneously. Has anyone else experienced this issue? This is the first and only issue I have ever had with an update, but unfortunately has turned me off from the iphone bigtime. Any help would be appreciated. Thanks.