Help, my PS4 "O" button won't work

So i just booted up my PS4 and things started normally. Started farming for blood vitals in bloodborne and noticed how from time to time my "O" button does not workl. So, i thoight, "Hmm, must be a messed up bug in the bloodborne update" so i thought. Then it later got harder to press. Then i celebrated my first victory in the third boss in bloodborne. Mind you, i did not drop my controller or rapidly tapping the fudge out of my controller. I then prceeded to hunters dream and inspected the tombstones since i've got the chalice. But then started noticing that it won't respond when i pressed "O". So i press the PS4 button to go to the home screen and tried pressing "O", but then nothing's happening and so on and so forth. I do have a second controller but i fear that the controller i'm using now might be broken. Can someone please help me.