What is going on with me

Ever since my son was born Ive started getting these intrusive thoughts. The worst is 'I just want to die' or 'just cut yourself'.
Now, to be clear, I have no conscious desire to die. I have a nice life now and I havent had the PPD issues this time around that I had with my first son. I dont know where these thoughts are coming from. It seems to occur randomly throughout the day and it scares me. Why are thoughts like that popping into my head? What the hells wrong with me?