I had braces and my bottom teeth are beginning to shift. what options do i have besides braces to get my teeth straight again?

Retainer: If the shift is minor , you can have a retainer , or invisalign done and bond a lingual (back of the teeth )wire retainer.

Invisalign: Unfortunately, once your teeth move they need to be orthodontically moved again.

Invisalign: As we get older there is an increase chance of crowding as the cuspids become narrower with shrinkage of the jaw bone. From what you are saying keep it simple and avoid full braces again as invisalign or active spring retainers work well.