Are you chewing normally on the other side or are you putting pressure straight on the new implant?
Because if the pain showed up after a few months of peace, it might be that you're putting too much pressure there without realizing it. An integrated implant shouldn't hurt just from being integrated, so something changed. It could be anything from a bad bite (the crown is hitting harder than it should) to a small inflammation that hasn't turned into an infection yet, or even the bone around it reacting to uneven pressure.
The thing is, if it started hurting now, it's worth getting an X-ray to see what's going on in there - sometimes infection starts subtle and only hurts when you chew because it moves the implant a tiny bit. But it could also be something much simpler, like you're clenching your jaw at night (bruxism) and it's causing inflammation. Go back to your dentist urgently so he can examine it, ask for an X-ray if he doesn't offer one, and mention exactly when the pain started and what makes it hurt more. The sooner you figure it out, the better.