Under eye is slightly swollen and feels bruised, very sore too touch. allergy?

Probably not: Allergy can cause swelling under the eye and cause the area to look dark, like a bruise, but not soreness to touch. Your question implies only one eye; "allergic shiners" will always be present under both eyes. You should have your doctor evaluate this.

Nope: Allergy not tender to touch. Sounds like sinus disease or infection of the lid. See doctor if not better in day or two.