Sorry you're not feeling well. Couple things to think about: allergies, sinus infection, drainage. Perhaps they could even be inter-twined. Headaches could be from sinus pressure, nausea could be from drainage. Lightheaded also sinus backup. I am not a Dr but when I feel like that I try some over-the-counter Zyrtec for a 3 or 4 days and see if it helps my symptoms or I might try some Sudafed PE. Sinus/allergies can also make you extremely tired and worn out. If your eyes are watering/itching chances it would be allergies. If not, most likely your sinuses. When my sinuses act up I can not function I get so tired. Hope pieces/parts of this help. Try calling your Dr and running through the symptoms they might have some over the counter suggestions. Sure hope you feel better soon. God bless!