Bushwacked – Two things I found incredibly helpful when I was having issues not unlike yours were low doses of antidepressants (amitriptyline) and swimming.
If you can get your arse down to a local pool a few times a week and are physically able to stay afloat then I would recommend swimming above all else. You can work on strength, cardio vascular fitness and stamina without having to push yourself too hard.
If you can only manage 1 length or just float about and splash a bit, then no problem. Next time just set your goal a tiny bit higher. Before you know it 2 months down the line you will feel so much better. Just don’t overdo it.
Combined with a low dose of antidepressants I think it’s a good way of getting back on track.
Best of luck mate.