My betta is turning pink and has dents(?) on his body

Uyu is a betta I brought home from PetSmart at the start of July. This is my first fish pet ever. He has made some transitions in the span of three months that I’m worried about. I will attach videos of him in order of the timeline. He is a premium platinum male betta and at the start(July), he was completely white like milk. He only had one red spot on the top right of his head. Throughout August, he started turning a pale baby pink, which I figured was just marbling. His body still looked smooth and clear of damage. Now in September, he has red ish spots on his head (left side) and two dent like spots on his body (left side) and a vertical reddish line (right side). His tale also looks increasingly dirty. Is he just maturing or is something terribly wrong ? I am taking his tank water to get tested tomorrow morning. His personality has also somewhat changed. July- He was shy and reserved (understandably) when I first brought him home. August- he was warmed up to me, followed my finger around the tank and was generally graceful and calm, moving smoothly around his tank. September- he still swims gracefully and calm, though he keeps swimming back and forth (left and right) along the bottom front of the tank. He doesn’t follow my finger as diligently anymore. And he’s started to act like he’s starving, jumping out of the water to get his pellets when I open the feeding door. I feed him 3 pellets twice a day. I would appreciate any insight and advice!! Thank you in advance. P. S. Sorry for the blurry photos, these are screenshots of videos I didn’t realize we could only upload pictures here.