Spokes getting loose is usually an indication of insufficient tensioning of all the spokes in the wheel. Did you tighten the spokes yourself of have a bike shop do it ? Also, has your wheel been damaged in an accident or by hitting a bad pothole. If you need to replaced your wheels, you can by a good serviceable set for well under $200 such as these >>> Alex AT400/Novatec track wheelset | Retrogression