I'm sorry to hear how things are for you right now. Loneliness is horrible and if not tackled can be a perfectly natural trigger for depression, etc. The lack of motivation is a classic sign of both social isolation and depression. I'm sure it feels awful but it need not be permanent.
One of my favourite sayings is that if you don't like the way your life is then trying something, anything, different (within reason) is better than doing nothing. Is there anyway you could meet new people or make new friends among the people you know? Is there anything you are interested in that could become a reason to socialise, be it a hobby or further education? Is there anything at all you can do to change your routine, even if it doesn't directly involve others? Is there anything you wouldn't mind trying, just to see if you prefer it to plodding along? It sounds trite but taking you out of yourself is often the best medicine, many people recommend exercise too, walking, running, exercise classes, gym workouts, yoga, etc. They take you out of your mind and into your body and classes can be social too.
If you think that is too much or if you think you need to change your habits of how you think and feel then CBT is often a good path. CBT is basically just about learning good mental hygiene. There is a book by Dr David Burns, The Feeling Good Handbook, which is very good.
As far as meds go, some meds help some people and not others, some people don't respond to meds at all. Go back to your doctor and see if you can try another medicine and / or dosage and also think about asking to be referred for counselling.
Hope some of that helps a little. Feel free to post as much or as little here as you like, in your own thread or in other threads, it is a quiet forum but every post is certainly read even if replies can be slow in coming.