Samsung S2 constantly rebooting and switching off?

[Sadieforthehotheads]

Haha, lol what is my life.

I am sick and tired of this phone. Right. Ill explain. A few weeks ago i was turning on my phone after it had turned off completely with a dead battery and it was now on charge. A few seconds after it had turned on, it showed an app title bar with a cog with the text "android". yeah.
So i thought nothing of it. 2 weeks later. It waa fully charged i was bored, on my phone and i thought , lets check out the old instagram profile. so i scrolled to the page. btw it wasnt on charge at this point. and then it randomly rebooted. So, thinking how odd this was, it turned back on showing at least 2 seconds of a caution sign then turning back on. This happened once each day for 3 days then turned to 7-8 times a day DO YOU SEE MY PROBLEM HERE GUYS

This was bad because i use my phone for taking notes in class and when i hadnt saved and it just turned off i was so doomed. Needs to be sorted out asap