Indoor cat with a dry hacking cough for months, like a hairball that never comes up

What they asked

Hello, doctor. I need advice about my 7-year-old female cat, Lucy, who has been coughing for several months. She has several short coughing episodes every day, crouching with her head lowered and making a dry “khh-khh-khh” hacking sound, as if trying to bring up a hairball, but usually nothing comes out. I noticed a small amount of thick mucus from her mouth once; it didn’t appear green. Jumping and having zoomies can also trigger her cough. Otherwise, she’s doing very well: she eats, plays, has good energy, breathes normally between episodes, and uses her litter box normally. No obvious wheezing or open-mouth breathing. She’s strictly indoors, doesn’t hunt or eat insects, and my other two cats aren’t coughing. None of them has had visible worms in their stool. Lucy had a NexGard Combo spot-on treatment less than a year ago. About a year ago, I gave Lucy one prednisone tablet, and her cough seemed to settle for approximately a week. I currently have Predalone syrup (prednisolone 15 mg/5 mL) at home. I gave her one dose once but discontinued it because I wasn’t sure whether it was appropriate or safe. I vacuum regularly and try to minimise dust and dust mites because they’ve been an issue in my environment. I’m wondering whether this could be feline asthma, chronic bronchitis, lungworms or another respiratory condition. I’m on a limited budget and can’t afford a chest X-ray immediately. Lucy is also very difficult to handle, so tablets and inhaler masks can be challenging. I’d appreciate your thoughts on the most likely cause, whether oral prednisolone could be appropriate and how it should be used safely, whether lungworm treatment should be considered, and what affordable options might work for a cat who is difficult to medicate.