Hi from eastern Ontario Canada.
I just wrote a long post and lost it before it was saved, so this 2nd try is very short...

We are looking after Chippy a 7 month old American Red, since she was a 6-7 week orphan (eyes were not yet open). This is our first time raising a squirrel, we are learning mostly from the squirrel forums. Chippy became very attached to my wife who has been her mother feeder since the beginning, and me in second place.

She went through a very agressive period the last 2 months, mostly to me, but also to my wife, a lot of chattering, squawking and some biting.

2 weeks ago, we wanted to give her some freedom to run in the backyard for an hour or so, hoping it would relieve her frustration of being in a large pen and only running in our house 1-2 hours a day. Well instead of an hour outside, she took off the whole day and came back after sundown, scared, exhausted and very thirsty. That night she clung to my wife, fell asleep in her arms the house-robe and wanted to sleep in the blanket beside our bed, instead of in her nest box in her large pen in the living room.
She has calmed down a lot since then, mostly back to quite friendly with us and no more biting.

In the attached photo you can see she has lost fur on the back of her neck, it began doing this 2 months ago, nothing to do with her trip outside . We changed her diet a month ago, to Henrys healthy or picky blocks, 2 a day, and lettuce, apple slices, orange slices, blueberries and 2 small nuts a day. The water bottle on side of her pen is diluted mixture of water and apple juice. Has anyone seen this fur loss before, what could it be from ?

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