You must be exhausted! 4 month old baby in the house.
Here's the thing. Life at home doesn't really get back to "normal" until the kids start school, and you start to have a little more time to yourself, and once you've started sleeping again.
Your body went through something pretty traumatic, I mean, you had a baby. It's perfectly normal to not be as "sexual" as you were before. What the two of you should do is talk to your doctor, together, about any concerns that you have, and how to overcome any discomforts. Your doctor can back you up on how you feel, and help your husband to understand what you are going through. It's also good to talk about in case you are experiencing the slightest form of baby blues, or PPD.
Also, ask yourself why you're not in the mood. Are you tired? Are you uncomfortable with your post-baby body (like so many of us are)? Is it because the baby is always around?
Have you had any alone time, as a couple, or individually since the arrival of your baby? This can do wonders. For months, I felt like I wasn't even myself, like I was watching from a distance, as my physical body, in a zombie like state, took care of the baby. You two need to reconnect with yourselves as individuals, not just parents, so that you can reconnect with each other.
Congratulations on the birth of your child, and best wishes.