Want off this and back on sertraline!!!

I first started on sertraline and was up to 100 mg a day for depression and anxiety. Then my pain management doctor had me switch from that to duloxetine for the  same plus chronic pain. I am now on 60 mg a day. I made the switch pretty seamlessly. I went down to 50 mg of sertraline and then stop that and went to 30 mg. Now I am so unhappy. My pain is still there, I keep gaining weight, my belly is so bloated,  my sleep is terrible, and I am so emotional. I want to get off of this and switch back to Zoloft. I wonder if I can do that same seamless transition back. My pain management doctor is willing to drop me back down to 30 mg for a few weeks but I’m not sure if after that  if I can stop that and resume 50 mg of Zoloft. Has anyone here done that?  I gained weight also on sertaline but I don’t eat as much on the Cymbalta and I’m still gaining and so bloated.  I’m already super self conscious so this is messing me up even more.  

I thought it was just me but the bloating is terrible and I look like a football 

I know.  I absolutely hate it.  I am waiting for my pain doc to send my 30 mg tablets to the pharmacy so I can start tapering.  My primary doc said I could do the 30 mg for a week and then switch directly back over to Zoloft.  I was much happier on that med.  I hope I still get out of it what I did before I switched!!!