Visit a Dentist
and get that interdental space cleaned. Also that area and the adjoining tooth to be checked via RVG (digital Xray) if any other problems like cavity is there or not. If not then scaling in that area followed by some mouthwash and antibiotic will be more than enough to get it healed. If there is more space in between the tooth and I'd food get lodge in that area then permanent solution is to go for a Crown to close the space.