I cannot understand three sentences.help!

[Jenny Lau]

1.If it's possible to see red about not seeing red, that is what I was doing. (“see red about not seeing red”, .what does it mean?)
2.I could feel the tension send warning stabs between my shoulder blades. (Was her shoulder very painful because of her unhappiness?)
3.A stone glimmering with fool's gold? (What’s “a fool’s gold?)

The following is the context (sorry, the context is long, it will take time to read)

If it's possible to see red about not seeing red, that is what I was doing. We had misjudged the timing of our autumn trip to see the changing leaves in the Great Lakes states, and I was really upset. No matter how I strained my eyes, I couldn't spot red anywhere.
I recalled an earlier leaf-viewing trip to Vermont in October, and the splendor of the maples, birches, oaks and sumac that lined the roadway. By contrast this vacation was a complete waste. I sat alone in the backseat of our rented car and fumed as we drove north through the dull, dark green. In the front seat my husband and father chatted merrily, apparently unconcerned.
By the second day I could feel the tension send warning stabs between my shoulder blades. This is ridiculous, I thought. I couldn't change what was beyond my control. How could I get out of my funk?
Then an adage came to mind: "Happiness is a decision." It must have been something my mother said. She was always passing on words of advice. When I was a child she gave me a little black book with empty pages. On the flyleaf she had written, "Look for a beautiful thing and you will find it." I was supposed to keep a record of the most beautiful thing I saw each day.
I remember spending hours debating what I'd write down. A baby's dimpled smile? A stone glimmering with fool's gold? Pictures in the clouds, or tulips tipping their heads? I found so many things it was impossible to pick just one.

[Casiopea]

The phrase to see red is an idiom. It means to be upset or angry.

If it's possible to see red about not seeing red, that is what I was doing. We had misjudged the timing of our autumn trip to see the changing leaves in the Great Lakes states, and I was really upset. No matter how I strained my eyes, I couldn't spot red anywhere.

The writer was upset because s/he wasn't able to see the leaves turn red.

By the second day I could feel the tension send warning stabs between my shoulder blades.

When some people are stressed, they tense their neck and shoulder muscles. That kind of tension results in muscle spasms (warning stabs)on the upper part of the back, between the shoulders.

The writer says, "this vacation was a complete waste." S/he is upset/stressed that the vacation plans did not go as planned.

A stone glimmering with fool's gold?

Fool's gold looks like real gold but it's not. People are fooled by its gold color, but they are happy when they find it. Fool's gold makes people feel lucky!

The writer didn't feel lucky on this vacation. S/he thought she would see the leaves turn colors--thought she would be lucky on this vacation, but s/he wasn't lucky.

[RonBee]

That's a very good answer. :D

• (Fool's gold = iron pyrite)

:)

[Jenny Lau]

Thank you for your good answer, Casiopea! That’s very helpful! But for the last question, it seems that this sentence has nothing to do with her unhappy vacation. It was only a game she played with her mother when she was a child. Her mother asked her to write down beautiful things and A stone glimmering with fool's gold is just an example. What do you think?
And thank you, RonBee.

[RonBee]

Thank you for your good answer, Casiopea! That’s very helpful! But for the last question, it seems that this sentence has nothing to do with her unhappy vacation. It was only a game she played with her mother when she was a child. Her mother asked her to write down beautiful things and A stone glimmering with fool's gold is just an example. What do you think?

I think you are right. :D

And thank you, RonBee.

You're welcome.

:D