It sounds just like you're running yourself off your feet, except I don't think you would be posting about it if that were all it is.
The sinus infection may have had a bigger toll on you than you realized, too.
Have you been somewhere very dry/desert lately? I don't remember where you're from. We have a fungal infection here called Valley Fever here which gets into your bloodstream. I had three months a couple years ago where I was excessively lethargic and toward the end of it I was sleeping 20 hours a day, only waking long enough to shower, change clothing and eat meals. My Valley Fever test results were inconclusive, and every other possible test my doctor could come up with was negative. I needed Dr. House to diagnose me! In the end, it may have been mild Valley Fever (yes, 3 months of not functioning would be a mild form of it compared to how sick it can make people) and my doctor thought the repeat sinus infections I had been battling at that point in time ran down my immune system and caused it in the first place.
I do hope it's just a vitamin deficiency which you can easily remedy, though!