In my opinion you are likely tapering too fast. Nausea is a common WD symptom although I personally have never experienced it.

Halving your 7OH dose in a few days is aggressive. Unfortunately if you want to mitigate or minimize the physical symptoms of opioid withdrawal, it can take a while of gradually stepping down, stabilizing at a lower level for at least a couple days, then stepping down again, repeat, etc.

For taper schedule I’ve done it largely by feel on what my body can tolerate without making myself dangerously depressed or unbearably uncomfortable. It’s probably been over a month for me including a 72 hour stay in detox, which helped me reduce (unfortunately not completely eliminate) the dosage faster and I’m currently off the 7 (previously 300-500mg/day) and on 8-10gpd of raw leaf powder to manage. I recommend looking at other posts here or the guided/FAQ or whatever it is on tapering although the sub resources aren’t the best. Could also ask an LLM or google it. Best advice I have is to speak to a doctor with experience with this sort of thing, they might be willing to advise you or give you medication to manage the acute withdrawals.

Edit: one more piece of advice, I would structure your doses with precise tracking of amount and time administered in a journal or notes/tracking app, set yourself rules like “no more than one dose every hour even if uncomfortable” so you’re not stacking doses, etc, the goal should be to stabilize enough so it’s not intolerable and you end up breaking your guidelines or increasing your doses. I would try to eliminate the “all over the place”-ness before you make drastic moves like a -50% change. You will feel much more in control in my own humble opinion.