Samsung Galaxy S4 — PROBLEM WITH MY S4 WHEN IT STARTS.

I bought my S4 5 months ago. Everything was fine until 4 ago. The phone got really hot and it was not turning down. I took the battery off to check the phone but everything was fine. Since then the phone is really slow, it consumes a lot of battery, it seems that I can not start up properly, it can not ready very fast the memory card and it starts up again by it self and then it works. I also notice that it can not save data to the memory card, by the way the memory card is the original SAMSUNG with the 32G.