the ergonomics struggle

Just started working at a new office. Small, private practice. We have four operatories, two for hygiene and two for procedures. None of the doctor-side operatories are set up ergonomically. One of them is truly awful, so the other assistant and I avoid that at all costs. Even the main one is a huge struggle though. It's a struggle to see the patient's mouth. The dentist also has TERRIBLE ergonomics. It's so terrible that it's funny: squatting, bending over the patient, looking upside down at the patient, just comically exaggerated but actually real. I've already told the dentist that sometimes I can't see the prep, so he'll have to guide the suction etc in those cases. I'm soooo sore after work, even after stretching throughout the day and getting a weekly massage. Of course, the massages are expensive but at this point I need them in order to be able to function. Even then, sometimes my left arm tingles and feels like it may go numb. I'm in near-constant pain. I feel alone in the struggle because this doesn't seem to affect anyone else in the practice, at least not that they talk about.

I have been an assistant for five years, but this is probably the worst ergonomic environment I've been in.

Any advice so I can make my job sustainable?

I'm taking a continuing ed class on ergonomics later this month and the dentist has asked me to present what I learn to the staff. Any tips on how I can convey the information in a non -judgemental way that will actually affect change?