I find that poor bankroll management not having a strategy for your game and for the level of risk you are taking and also not being used to variance can create these feelings.

Also playing for a reason such as must make x/hour creates issues like this. If you are enjoying what you do and want to learn more/develop then I think that is the easiest way to avoid serious tilt issue. Also play less tables and have a strict timetable for playing should help.