It sounds like you may have S.A.D. -- Seasonal Affective Disorder. Have you noticed this when other seasons change, like when winter is changing into Spring, or Spring into Summer, or Summer into Fall, etc.? It can really throw alot of us for a loop.
I have SAD and oh brother -- if I wasn't on an antidepressant, I'd probably be in the nut house. LOL Even with the A/D, I can STILL feel some sadness and a bit of the blahs.
Why not talk with your doctor about this and see what he has to say. He may want to send you to a therapist or put you on an A/D. But Seasonal Affective Disorder is REAL and it affects millions of people. So talk to your doctor. He can help. God bless & please take care. Hugs, Lee