Sorry, I missed your previous post. If the coughing still hasn't gone away, my only recommendation is to get Oscar back to the vet - and get an x-ray to see if there is fluid in his lungs or around his heart. If so, your vet should put him on a diuretic, and that should clear him up. If not, he might have bronchitis.
After Jake was on his meds for a couple of weeks he's back to his old self - not coughing at all any more and playing too!
Also, do you have him on a good food? I also switched Jake over from Weight Control Iams to grain free canned Wellness, so I don't know if that had a hand in it as well.
Good luck - I hope Oscar will be back to his old self!
Taken over by:
Jake - grey DSH (Aug '98)
Alley - spazzy grey tabby (Aug '07)