I have my left side of my butt cheek has a big dimple and it is noticeable, how can I fix that? Help please. (Photo)

Fat grafting would improve this area for sure. Hopefully the indented area is not scarred down which would limit the result. Seek a consultation with a plastic surgeon who does a lot of fat grafting. Good luck.

Hello dear!
Thanks for the pictures and provided information as well.
Based on your photos, you are a good candidate for fat transfer to fix your problem, and I think you'll get very good results. 
l recommend you to make an in-person consultation with a board certified plastic surgeon for a proper answer and to talk about your goals and anything you need to know.
Good luck :)

There are a number of ways that the "dimple" may be corrected including fat transfer as well as fillers. You need to consult with a Board Certified PS. Good luck!