Yesterday morning I shoveled snow before eating or drinking. when
Difficult to assume the cause...
I went through the details with diligence. It's difficult to assume the cause of dizziness, nausea and loss of posture (fall to the floor). There are few conditions that may cause these symptoms. And lots of coffee consumption hours before the event are one of the cause. In such cases it is important to check blood pressure, blood sugar as well as cardio examination. An EKG is warranted.
If you are feeling well now and do not have any more light headedness, we need not be overly worried. But I will urge you to see a primary care physician.
Hope this helps. Let me know if you need clarifications.