Is This a Double Bubble? Is a double bubble painful? (photo)

This appears to be mild and in my experience most patients self correct with time. I typically have my patients wear a bra and cut out  a segment of it where I want the breast to expand (the lower pole in your case). If after a year it is still present you can consider fat grafting as an office procedure.

The "double bubble" look after a breast augmentation is usually the result of having a tight crease at the base of the breast that does not relax after surgery and an uneven cover of tissue over the implant.  It is not usually associated with discomfort.  The pain you describe may be pressure associated with stretching of tissues in the early post operative phase.  If it does not resolve check with your surgeon.  

It looks as if your surgery was relatively recent.  In the area that is shown in the photo, the ridge may very well be your old crease under your breast which needed to be moved in order to accommodate your new implants.  Sometimes there is temporary swelling and bruising in this area that resolves over time.  If your surgery was some time ago, I would recommend an evaluation with your plastic surgeon to see if things can be improved.