Mom is on the verge of not being competent, but still knows all 5 kids. Had a trust made 16 years ago. No one minded then I had POA. But now, brother is with Mom most and we don't always agree on what is best. I am spent. Do we HAVE to get a lawyer? Or is there a simple way to change?
Who made the determination that your mother is "on the verge of not being competent"? If other than a medical professional, and this is just a personal observation, it would be up to your mother to revoke the existing DPOA and execute a new one. This is the best option.
But because of the friction with your brother, it would be worth it to spend the money and have a new one prepared by an elder law or estate planning attorney, if your mother is still able to make those kinds of decisions.