Maybe you do something in the evening that triggers inflammation and swelling ?
Mouth wash ?
Hair shampoo ?
Face wash ?
Indoor Plants ? (Could be an allergy to plants inside the sleeping room ) ?
Could be an allergy to pesticides used inside the sleeping room ?
Could be an allergy to laundry chemicals used for bedsheets, any softeners ?
Could be an intolerance or an allergy to foods or drinks consumed during the evening or afternoon ?
Or something special you do only during the evening?