This is a very complicated question, and your doctor's actions are a bit confusing. buprenorphine has a 'ceiling' to the effects it creates, and that ceiling has effects about equal to the effects of taking oxycodone 60 mg. If you give buprenorphine to a person who is taking nigh doses of oxycodone, you usually cause withdrawal. I am surprised that you were able to add a buprenorphine patch, while taking oxycodone, without getting withdrawal symptoms.
Depression is very common during opioid withdrawal, and is the worst symptoms for most people. If you became depressed when the buprenorphine patch was started, I would not be surprised. Likewise, it is common to become depressed during reductions in the dose of oxycodone.
There is little that can be done for those feelings, other than to try to reduce the dose very slowly. Even then , there is no way to avoid it completely. But at some point, it simply has to be done.
If u really wanna know read my post under addictions if u wanna stop DON'T START SOBOXONE. Better to withdraw for 7days then what iam expirancing now