I really feel for you Kate. It sounds like you are having a bit of a bad time at the moment and your body is wanting a break and some feet up time.
I know how you feel. I stopped smoking in October, thought I would feel great in no time. How wrong could I be? I had chest infections all through November and Christmas time, struggling to breathe continuing through January and last two weeks not too bad. Good, I thought, it's getting better. Wrong again. It came back this week. Bad again from Thursday.
So, time to put the feet back up, stop thinking about the decorating that needs doing etc (we moved recently) and to take things easy. Get out the honey and lemon, Vicks vapour rub back on the chest, Olbas Oil for inhalations and lots of rest and sleep. I do have a ventolin too.
I would just give in to it for now. It hasn't really been that long if it was January. It does take time to recover. Do it slowly but don't give yourself a hard time if you don't feel up to doing anything. Put on your favourite dvd, soak your feet, do things that make you feel a bit better. If you feel tired, sleep. I think we don't listen to our bodies enough in our society. But enjoy the time you do go out and see friends. It is nearly March now and the flowers are starting to poke their little heads out and say hello. The lambs will soon be playing poker in the fields (gamboling). Take a ride out soon and see nature unfurl it's winter coat and stretch. Slowly, hopefully, your mood will lift and you will begin to feel better again. Just go easy on yourself until then. 