I would try uninstalling and re-installing. I would also turn off the Music and Sounds. Play around and see if it crashes again. If not, try turning on the sound again and see if that causes the crash.
I normally tell people to turn off the music because the game is REALLY buggy and having music/sound on together has caused many issues with my friends. If you have a mid range device, having sounds on will cause plenty of lag.
Oh, yeah, if I left notification sounds ON, the moment I got one the game would mute and would start to get laggy.
Oh, yeah, if I left notification sounds ON, the moment I got one the game would mute and would start to get laggy.