Three things:
1. Make sure that the battery isn't loose and that the circuit contact points are aligned.
2. Make sure that you've got the latest updates installed on your phone - Settings > phone update.
3. Take your phone to a service center and have them diagnose the problem. If they find a problem, make sure you also inform them about the touch screen issue - L535s in other countries have had their screens replaced under warranty to completely resolve the touch screen issue.