I'm really concerned about my mom. She's been coughing for about 45 months now. We've seen both general and ENT doctors, and they've done a chest, nose, and throat X-ray, but everything looked normal. The doctors just keep prescribing antibiotics and allergy meds. They help for a bit while she's on them, but as soon as she stops, the coughing starts up again. What else can we do or look into to figure out what's going on?