Not only do you feel crummy from the cold or upper respiratory infection with watery eyes, sneezing, chills, achyness, and gunk coming out of you nose-
but the infections cause your head to become woozy!
When you have any form of infection, there is swelling of the tissues. Add the mucus factor and there is your stuffy feeling. No air is passing thru your nasal passages and if you have infection there (colored mucus) you really got it bad.
Your face is a very hollow area with many sinus cavities that should be open for good air flow. When you get the swelling, infection & mucus in there, it makes your head feel heavy- because it IS. The sinus cavaties are porous and light, but if your infection is bogging you down it can actually increase the pressure in those hollow areas and create that lovely dizzy, light headed feeling we don't like.
Also, many ear & sinus infections cause swelling in the ear canal. Your sense of balance (equilibrium) is controlled here. If there is swelling in your inner ear and it affects that area, so easily can have trouble with feeling woozy.
Get plenty of rest, boil some water in a kettle on the stove (it adds moisture to the air in your house), drink plenty of juice and water and I hope you feel better soon! Take Care!