I wasn't going to respond because I agree with everyone else about the depression part...but the more I thought about it, the more I realized that sometimes hearing you're "depressed" is only as useful as getting you into see a doctor. And many doctors aren't clinically trained beyond prescribing, which helps in some ways, but not in others.
The recommendation to see a therapist is a great one because I sort of think you need social connection most. It sounds like you don't have anyone in your life except for your spouse and son. And to be honest, even if you don't feel like being around others, it might actually help give you a 'break' from whatever thoughts and feelings seem to be dominating your life experience thus far.
Your son is a year old now and maybe finding a play group to take him to will not only provide him with important social interactions, but will also afford you social interactions that force you to interrupt what seems to have become a form of rumination of sorts.
Exercise is helpful in terms of making your biological chemicals influence mood, and prescriptions and evaluation can also address the biological influences.
I think the Peg M. had a great idea to explore what your needs are? It sounds like you are in a new city with very few social connections. In a way, it's a fresh start...clean slate? What are some things you've always wanted to have time to do but never did? If energy is getting in your way, maybe start small by cruising the internet on topics of interest that can be found in your new city? Maybe there's a group of people with similar interests you can connect with on the same level?
I know that when I felt depressed, the last thing I wanted to do was be around others and I couldn't feel desire to do much of anything. I lost the ability to 'enjoy' things that I once truly loved doing. So I didn't do them for me...because doing something for myself is way harder than doing it for my son! But I really wanted my son to love life and be an active participant in his life. And the more I thought about it the more I realized I was his introduction to the world and if I didn't enjoy life or myself or others, how the heck was I going to instill this in him? So I made myself go to groups I didn't want to go to and made myself go for walks with him when I really really really didn't want to. I "faked" it. And to my surprise, after a few months, I caught myself smiling in a genuine way and making plans with new friends with genuine happy anticipation.
My life looks nothing like it used to a year ago and I think that was part of my problem...new identity, new friends I didn't know very well, and the new role of mama. It was all so unknown to me that it was scary and I wanted to keep to myself. But as I started to form a new identity, incorporating elements of my past self that I truly wanted to keep, I began to realize I could do this and even like life in ways I never dreamed possible.
There are ups and downs in life, and I'm sure I'll have down times again, but I guess I wanted to share my experience in case it was helpful. For me, staying trapped in my head wasn't helpful, though most desirable for sure! What helped most was therapy and forcing myself to form social connections...and darn it, it worked.
Best of luck to you and please know that it can get with time, patience, willingness to switch up your routine, and most of all with some compassion for yourself. Just because you feel bad doesn't mean you are bad and just because you feel stuck doesn't me you will stay stuck. Just pay attention to your needs and recognize by doing so, you are also taking care of your sons needs because a happy mama makes a happy baby:)