Why does my phone lags and automatically turns off and on?

My samsung galaxy's software seems ok? I don't know it's just everytime I use it and did something that will make it lag like multitasking or sometimes it really lags out of the blue it will usually turn off and will turn on or it will be stuck in the Samsung Galaxy logo until it overheats, then vibrates and the loop will repeat again, for short, it's a never ending loop of turning off and on. It really irritates me these days bc It won't successfully turn on now. If it does, I can only use it for minutes then it will turn off again. What is the problem with my phone though? Is it the battery or it's inside the phone? Any tips of how can I fix it or should I go to a technician now?