What happened to my arms?

I’m wondering if anyone has experienced similar? 48 and in Peri. Started noticing my arms starting to change - not crepey but more like getting cellulite all along the bottom of the arms and the skin becoming old or aging - almost overnight. They went from toned to loose and bumpy. Has anyone else experienced this? I’m so sad about it as my firm arms were some of my features I really held onto.

Gonna start weight training but I’m not sure it will help. Anyone have advice please for what is causing this and how to stop or reverse it?? TIA