I got the same problem. I document everything that happens every day at lunch and then again at home. File for everything that is harassment. Switching workloads, areas, trucks, start times, excess overtime, no overtime, seniority, etc etc
I do not file on little stuff like a sup moving 1 box from driver a to driver b on another belt or bringing me a new diad but on anything big I file.
Call the 1-800 number as well. Never get cornered in an office without a steward or a witness you can trust. Never talk to managers without a steward period.
Say as little as you can. Do not load the gun for them as they say.