[Acne] Is multivitamin/vitamin b12 induced acne permanent?

Hi. I have been breaking out in the face and back and I suspect that it was because of the multivitamin that I stopped taking a month ago. My acne started to get worst around those time too. I didn't have much issue about acne for most of my life so having this took a toll on my confidence and mental health. I'm currently on doxycycline + clindamycin (liquid) + erythromycin gel. It's been a month and I'm still having cystic acne plus the post inflammatory erythema isn't going away. My dermatologist wont prescribe me anything other than those mentioned and I am not allowed to try other products as of now.

Does anyone here had the same experience? Is multi/vitamin b induced acne PERMANENT? (because I am afraid that in my case it is, I have been seeing people resolved theirs within a week or two while others go on accutane) if not, how long before it cleared up?