Preoperative images should be seen and assessed, it is unclear whether your sliding genioplasty was poorly planned / executed, leading to an overly protruding chin... or even it was not indicated at all; in any case, the advancement went too far, that's why the chin prominence is protruding so tightly under que soft tissues and making your mentalis so tight, looking artificial (ball chin). If you get botox on the mentalis... you'll get a palsy incompetence to push up the lower lip and you'll be drooling, unable to speak, contain the food bolus and express yourself, with an awkward facial look, during 6 months and probably some residual effect may persist for a lifetime... has anyone lost the commom sense here? And it is not yourself. Additionally, I bet you have double chin deformity when smiling, with soft tissue dislocation, because it seems to me the mentalis tendon was completely detached from the osseous surface and is loose, just a gut feeling based on your look and my experience in genioplasties, the latter of which is not small. I also bet the surgeon used plate and screws to fix in place the osteotomy for the sliding, instead of steel wiring like I do; why do I think so? Plates do not allow for milimetrical calibration, they can be bent a little and allow some flexibility, but very little if any, so it is common poor adjustments like in your case. Now, you need to find a very good surgeon with real experience in all types of genioplasties, reduction, augmentation, sliding, primary and revisions, and assess your situation to reverse in part or in full this far fetched forwarding you got done. Needless to say, DO NOT get any Botox or fillers, for God's sake...