You should get this fixed right away at a body shop before it gets worse. I own a 96 integra and I had it since new and it was only a year ago that a friend of mine told me that all hondas and acuras come this stupid rubber strip inside the wheel well that should be removed and wheel well should be professionally repainted.

When I removed it, I found some rust just starting to form. My friend told me that if I had taken that rubber strip off on both rear sides when the car was new it not have started to rust because the rubber strip keeps the moisture trapped inside. Honda Motor Company is to blame for this by causing hondas and acuras to prematurely rust unessecerely. Those rubber strips should never have been put there in the first place.

Get your car to a body shop, have them remove the rubber strip, remove all the rust and paint the rear quarter panels over again.

By the way, don't forget to rust proof it afterwards. And the cost would be at least 500 Us dollars to have a good quality job. For 1500 Us you could do the whole car but be careful where you take it because some autobody shops do shitty work. Either way. it depends how long you are planning to keep the car.