Infected or not?

Okay let me start off by saying I've had my belly button pierced for the past 4 YEARS. Never really had an issue. I usually change my belly button ring every few months or so and it's usually fine. However, I just changed it a couple weeks ago (and it was fine) but then a day later my belly button got red and swollen and hurt (it was even a little hard) so I thought it was the jewelry and so I took it out and switched it. I switched it to another one but it did the same thing so I finally switched it back to the original jewelry I've been wearing for the last few months or so that I've had no issues with. However its still red and swollen and hurting. And yes I have disinfected and cleaned my jewelry before putting them in but it's still doing this and still hurts. I have no idea why considering it's been fine for the past 4 years! Is this infected?