Could I have an air pocket under a dental implant?

I had dental implants on the bottom and have had them for about 7 months. Recently I had them taken out and cleaned. They were X-rayed by my Implant Dentist. They were very clean and my gums were very pink. But I have had pain in the furthest implant to the back. It is more like an aching all the time. He did not find anything wrong. Is this normal? What do you think my next step should be?