SOLUTION (for me anyway)
Morning Chaps,
I had this issue ( gimble pitching up and down, unit turning left and right) develop a few months back and it started to worry me, so i turned to google and found you guys.
After re-calibrating, flashing the software and shouting at it - nothing changed. It dawned on me to check the warranty and let DJI tackle it.
On their report, it mentioned a fault in the RC controller and simply said " Rc dial module defect".
They've replaced the rc unit and everything is awesome again.
I only write this in case any is googling this issue and pulling hair out.
Good luck !