I lost my toe,
the foot went grey.
Where I used to know,
A hole does stay.
I found my egg,
in a ditch was where.
A root now my leg,
the trench now a pair.
I swapped my tree.
And "oops" in the past,
(Where could I be?)
became "ouch" in contrast
Where on earth am I?
Hint:
What I lost sent me from high to something just below
What I found sent me falling even further though
What I swapped sent me going between high and low
Hint 2:
Adding the letter
n
somewhere on the first line would give you a massive clue.
Final Hint:
It's important that you change your tune or die a critic.