Doxepin taper started and feeling heavy and hopeless

Hello, I need some help. I feel really hopeless. I've been battling a nervous breakdown for the past 18 months. I've tried a number of SSRIs and have been trying Doxepin (TCA) for the past 9 weeks. I recently started tapering off of it on Nov. 1, so 6 days ago. I actually felt good for the first time in months two days ago, but now I feel absolutely hopeless and brain dead. I'm insanely depressed and feel super heavy. I called in sick to work today and I work from home! I guess I'm wondering if this is to be expected? I'm really scared that I'm never going to come out of this.