Volume loss in cheek after Botox on masseter (Photo)

Had Botox on tha masseters and only one side took which was my left side. Unfortunately, I have volume loss on the left cheek around the nasal labial fold and now the smile line is longer passed my mouth and deeper. It’s been almost a year and it has not changed. I believe this is permanent. Is it deteriorated muscle tissue or is it fat loss? I need to know what procedure will rectify this. Sorry photo is upside down