Manager is ambiguous and sneaky

I got slightly lower rating than meeting expectations- atleast I think so. Ever since then manager has been trying to collect proof I feel. Created a recording of the meeting for the estimates Doesn’t give much feedback on face but slacks me after 1:1 and sends me messages there . This has happened twice and over small stuff. Asked me to work on another project with another manager. I feel like a pip is incoming but when I ask him he says no pip or no firing. I have a major chunk of vesting happening in April and this is making me very anxious. Should I just take fmla to avoid anything bad. But this could lead into catch 22 situation where fmla becomes the reason of firing. Also can they fire during fmla.