Hey Augusta i feel your pain, girl.. I've been waxing steady for 10 years and have developed chronic back pain. I think hip high is pretty accurate, sometimes i have it higher. I find my pain is worse from reaching/twisting for wax . instead of turning body to dip stick i just sort of twist. I have had to become very mindful of posture and positioning since my injury. I've been through p.t, injections and chiropractic. Sadly as my chiro said, what i need is about 3 weeks off to heal up, but who can do that?!? Hopefully you are also considering proper shoe. I have had to go into orthotics and i feel a huge difference when i try to wear cute heels or something. so yes, i have old lady shoes, but they make all the difference. Where is your waxpot when you are doing brazilians? Do you keep it on the side? Just try to adopt a "fencer's stance" when doing braz's. This way you won't be bending or straining too much. Wish I can help more. I try all these things and still deal with pain everyday. Have you seen an ortho? had an mri? might be good to be sure you are not dealing with bulging/herniated discs. I hope you feel better!
yes flats are awful for lower back! orthoheel has some cute styles. I had 7 brazilians today and am currently sitting with an icepack on! I know you can't stop doing brazilians they are great money, but if you continue straining you will only make things worse, and your health is of the upmost inportance. I would also suggest a nice, well crafted back brace. Not the prettiest things, but if you wear a professional smock of sorts it will go unnoticed. they really do aid in forcing you to keep your back straight. Google search fencer's stance. This is achieved by almost lunging one leg in front of the other while so leg takes the brunt and you do not have to bend. Ugh. no fun. I think my time doing this is limited because i ignored my pain for so long. Don't do that!! See a doc and take care of yourself!
In addition to possibly adjusting your table height, I would suggest booking a massage at least once a week or once every 2 weeks as a part of your self care. Try to avoid steroid injections if at all possible, they create scar tissue which may make the problem worse in the long run. Try massage, chiro and pt first. Also, some stretching would help or try laying on the floor with a tennis ball in the spots that hurt and just take some deep breaths to release the tension. Hope this helps!