Suggest Treatment For Sore And Painful Toe

The top of my roommate s right foot is hurting (id say its the area above her second biggest toe, around the metatarsal/cuneiform area) in a line going up and down... she says its sore when she walks and sometime without wearing shoes. Also since this morning it has a fluidy sound/feel when she moves it (up and down). When I make her relax her foot and move it myself I dont hear any sound. I checked the rest of her foot and there seems to be no other sore/tender spots. She is 25..about 98lbs. The foot has been sore for a week. She has no idea how her foot got hurt. Also there is no discoloration and no swelling. What do you think is wrong with it and should she go see her doctor? Thanks