Contact vulvitis vs infection symptoms?

See your doctor. Contact vulvitis (or dermatitis in general) is an irritant dermatitis; it mainly has red skin, maybe something tender but more itchy than anything. Should only have scant, if any, discharge. A cellulitis, which is an infection, is red and usually very tender/painful, and may be associated with a pus-like discharge. I would talk your doctor about it.