Blepharitis: This is an inflammation of the eyelids that can cause swelling, pain, and redness. It's a common condition that can be caused by a bacterial or demodex mite infestation, making it a likely diagnosis for eye bag swelling and pain.

Allergic Conjunctivitis: An allergic reaction to substances like pollen, dust, or pet dander can cause eye swelling, redness, and pain. This condition is common, especially during allergy seasons.
Periorbital Cellulitis: This is an infection of the skin and tissues around the eye, which can cause swelling, pain, and redness. It's more common in children but can occur in adults as well.
Hordeolum (Stye): A stye is a localized infection or inflammation of the eyelid margin involving hair follicles of the eyelashes or meibomian glands. It can cause pain, swelling, and redness.

Orbital Cellulitis: Although less common than periorbital cellulitis, orbital cellulitis is a serious infection of the tissues surrounding the eye, within the orbit. It can lead to severe complications, including vision loss, if not promptly treated.
Cavernous Sinus Thrombosis: A rare but potentially life-threatening condition that can cause eye pain and swelling, along with other symptoms like fever and vision changes. It's a blood clot in the cavernous sinus and requires immediate medical attention.
Herpes Zoster Ophthalmicus: Shingles that affect the eye can cause severe pain, swelling, and potentially lead to complications like vision loss if not treated promptly.

Graves' Ophthalmopathy: An autoimmune condition associated with Graves' disease that can cause bulging of the eyes (exophthalmos), swelling, and pain due to inflammation of the tissues around the eye.
Wegener's Granulomatosis (Granulomatosis with Polyangiitis): A rare autoimmune disorder that can affect various parts of the body, including the eyes, causing inflammation and damage.
Sarcoidosis: A condition that can cause inflammation in various parts of the body, including the eyes, leading to symptoms like swelling and pain.