It could be PND but it could also just be the overall tiredness and stress that comes with a newborn.
Speak to your midwife, they can do a simple Q&A test to get an idea.
If you do have AND there are ways to treat it other than with drugs and the support is very good nowadays.
Just to add though that I have felt like this after both of mine, and didnt have PND.
Your body has been exhausted, and now your mind and body both have to deal with a lot, sleepless nights, worrying about caring for a newborn, the responsibility that accompanies parenthood and also you never seem time to look after yourself, eveyone else comes first dont they. I think it was about 4 weeks before i started to eat again after the birth of my second.
be open with your hubby about how you are feeling and Im sure he will understand and support you