Crazies

So I feel like I'm just losing my sanity. I feel on edge 24/7. Every time my 5 wk old makes a noise, I immediately tense up because I'm worried he is going to start crying. He has colic so of course we have long crying sessions. I also have a 2 year old and I feel like all I ever do is fuss at him and tell him to go play and leave mommy alone. I just get to feeling so agitated especially when holding the baby. My grandmother is saying I need to talk to the Dr about it but I feel like he will just be like, well that's part of motherhood. It will pass. I remember be on edge with my first son but this is even worse. If it was ppd, wouldn't I feel down and not just agitated and crying frequently?