Yikes, have you asked about lowering the dose of hydroxycloriquine? Obviously you can't stop taking it abruptly.
Perhaps ask them to call in a prescription for the nausea. I take ondansetron (aka Zofran) during a bad diverticulitis flare. That'a often given to chemo patients. The over the counter anti-nausea I've found effective is Nauzene. You shouldn't be miserable while dealing with this.

There are unfortunate problems that surface when people get into the neighborhood of 5 mg of prednisone after long term use. Prednisone supplies cortisol but suppresses your adrenal function. Your cortisol level is probably low at this stage of tapering. Your doctor is correct because it will be rough going at this stage because of adrenal insufficiency.
https://www.endocrine-abstracts.org/ea/0056/ea0056p44
The only way to get past this stage is to continue to taper slowly but some people are unable to successfully taper off prednisone completely.

That sick feeling you describe and overwhelming fatigue were my symptoms when my adrenals weren't producing enough cortisol. I also had muscle aches and pains but they were nothing like the pain I had when PMR was originally diagnosed.

Adrenal suppression is why we are told to taper off prednisone slowly and not stop it abruptly. I had adrenal insufficiency when I tried to taper off prednisone without a backup medication to help me control my inflammation levels.

Cortisol is a hormone that "regulates inflammation." . The backup medication that helped me was Actemra which kept inflammation in check while I tapered off prednisone. Actemra doesn't suppress my adrenal glands like prednisone does. There are other "steroid sparing" medications that may help. Hydroxycloriquine is one of them.

Fortunately, my adrenal suppression wasn't permanent and my cortisol level slowly returned to an "adquate level for normal days." My endocrinologist said I was still at risk on abnormally stressful days. It took about a year for me to start feeling better and my cortisol levels returned to normal.

Adrenal insufficiency and suppression of the HPA was hard for me to overcome. I took prednisone daily at moderately high doses for more than 12 years for PMR and other autoimmune problems. It is a complicated problem as the following link suggests ...

Good luck ... not everyone has a big problem. However, everyone will experience at least some problems after long term corticosteroid use.

Hi @johnarbaugh, You will notice that we moved your post to an existing discussion on tapering off of prednisone so that you can meet other members like @vellen @dadcue @suetex @sued70 and others to learn what they have shared. If you click the link below it will take you to the top of the discussion where you can read what other members have shared.
--- How did you cope with the side effects tapering off prednisone?: https://connect.mayoclinic.org/discussion/taper-side-effects/

I’m similar to you, I can’t go below 4 mg without flaring badly. I took HQC like you for a year but it had no effect on PMR, might have kept me from getting Covid lol. Prednisone is all that works for me so far.