Question:

I am new to fmla for about two months. The general manager has accused me of not using it for medical reasons and has threaten to take away my permanent desk and make me be a floater. I was very uncomfortable having to have to go into my personal health information trying to defend myself. I thought I was covered by having fmla and having my doctor fill out all the paperwork. I’m not sure what I should do next.

Response:
I assume that a company that qualifies for FMLA would have a Human Resource Manager or Director, if not a CEO.  I suggest you talk to one of them, but go prepared, bring any documentation that you have regarding your situation and what your manager  asked of you as well as names of witnesses who might have heard the conversation, if your manager sent email print them and bring them to your discussion with your employer.
If you have provided a physicians certification to your employer, there shouldn’t be further investigation unless the certification wasn’t clear.  Furthermore FMLA has build in protections for those who take leave, limiting the ability of employers to substantially modify the job of those taking leave.  Your Human Resource Manager or CEO might be interested in knowing what your manager has requested and the statements he has made.