I'm confused what you are asking us. There is a correlation that has been studied that cannibus can cause psychiatric symptoms that look like bipolar disorder. Is this what you are referring to? Or are you saying that weed makes your bipolar worse according to your doctor? And you still want to use it but aren't getting the high you want? If you can clarify, that would be helpful. https://www.scientificamerican.com/article/people-with-bipolar-disorder-often-use-cannabis-it-may-sometimes-help/ There is a prevalence of weed usage with bipolar patients but they do really discourage it.
You should go back to a doctor to see if your bipolar disorder is under control on 3 pills per night. You might not be the best judge of how you were doing, especially if you experienced mania before the meds. Weed doesn't create back pain.