My question involves labor and employment law for the state of: Oregon

My employer is a privately owned company with >50 employees.

I was recently diagnosed with narcolepsy and put on FMLA. Over the course of a month and a half I had several fatigue attacks that caused me to leave my desk with little warning. On the third month, I was placed on a side project with flexible hours so that I could acclimate to a medication that would stabilize me. It was my impression that as long as I was able to do my job, after the side project I would return to my normal position. Instead I was told that I could only return to my old position if I signed a statement that said I would no longer use FMLA time. My narcolepsy was managed, but it can't be cured, so I told them that there's always the chance that I might have symptoms. They put me on a fourteen day unpaid leave and said that if I still needed FMLA after that, I could apply for STD.

I was put on leave on 3/1, and I'm still on leave today. Since I'm able to work, and my sleep doctor told STD that I should be working full time, I'm of course ineligible for disability funds. I've gone back and forth with my HR department this entire time trying to come back to work, but they refuse to let me if I insist that I might need FMLA. Today, the vice president in charge of HR let me know that I can come back to work and use FMLA, but all FMLA leave has to be preapproved. If I have anything like a fatigue attack, that FMLA will be counted as an attendance hit. Then, if I would get written up for poor attendance, I may choose to go back on unpaid leave instead.

I'm not a lawyer, but isn't this not OK? I've told them multiple times that I am not having symptoms and probably won't have symptoms, but they won't let me come back to work until I agree that unexpected fatigue attacks aren't protected. My suspicion is that they're just tired of bothering with me and are trying to fire me one way or another. It's all been super shady; I've had to email them to confirm in writing what they've told me verbally, I've had to insist that my manager be copied on emails, and they spent forever poring over my project trying to find something wrong. I had to forward their email to the STD claims handler to prove that they said that sudden onset symptoms weren't protected. They also hired the temp that was covering for me.

Is there anything that I can do? Is my best course of action to just agree and go back to work?