Is a Change of Position while on FMLA legal if it changes benefits?

My employer changed my position while I was actively on FMLA (did not wait until I returned) and as a result, my benefits changed. I am on FMLA for a spinal issue, but my anxiety is making it impossible for me to contact my boss or even HR because I'm so confused and upset. I'm afraid to tell them that I may need the long term disability benefits that were changed and taken away from me just before I might need them. I can't believe that something like this is legal. Can anyone help me?

Since originally posting this, I reached out to HR because my boss emailed me telling me she was putting me on the schedule or terminating me, because my FMLA was up. The FMLA company is saying that my doctor cleared me for work, but my doctor is telling me he didn't. They want me to jump through a ton of hoops before I'm "off unapproved LOA." Can someone help?