My brain just won't function right now. Simple tasks have become extremely hard. My memory is poor. I am a senior sufferer of SAD in my 60s. I am weepy and losing the will to live. I am panicky, and cannot stand crowds. I want to bury my body in a hole and stay there. I fear being around others and don't want to talk. I don't take medication just suffer this awful depression until things improve and I can then emerge from this dark blanket which envelopes itself around me.
Your first port of call should be a trusted medical professional to check that the SAD symptoms that you have are not indicative of any other condition. I totally relate to everything you say, as I suffer like this sometimes. I hate crowds and noise at the best of times, but in the winter are unbearable.
I get through with a combination of antidepressants during the winter only, light therapy and lifestyle modification during the winter.