I haven't been able to put my finger on what was going on with DD until I ran across this article:
https://www.davidsongifted.org/gifted-blog/existential-depression-in-gifted-individuals/Lately, she's been questioning everything. She tells me "I don't like myself" and when questioned further it seems to be in part that she doesn't look exactly like DH or myself. Other times she says it's because she doesn't know what she wants to do with her life (like who she will marry, what job she will do, living on her own someday etc). We try to explain to her that is incredibly far off but she still freaks out about these questions. Sometimes she just tells me "you don't understand" and won't explain further.
She figured out when she was 4 that Santa didn't exist (a friend of ours had mentioned him and she got really upset about it and demanded we start telling her the truth). And this has made her start to question everything, if God exists, what things we actually believe in etc.
She also get a lot of nightmares at night. She constantly fears that DH or myself will die and asks if we'll still love her after we die or just questions about death in general. She's very interested in outerspace/planets/stars and asked when the sun would die. This has also added to her fears and she asks when people will learn space travel so that we can move to another planet if the sun dies.
If she does make a mistake or accidentally insults someone she holds on to it and won't let go. There are things she got in trouble for MONTHS ago that she still feels bad about and will start crying about randomly.
Mostly, she just comes to me with this stuff. DH gets frustrated on how to handle it. She said that she's tried talking to her nanny about it but she also didn't say much. I'm not even sure what to say most of the time but to explain to that we will always love her. I also tell her about my own childhood and things that I was scared about, how I also had nightmares and many of these same fears.
We've talked about possibly taking her to a psychologist. I don't even know where to start when it comes to finding one. We have a number of family members with mental health issues so that's an added concern for us...
ETA: I've also tried tentatively broaching this subject with a few friends of mine to see if their kids are asking similar questions but I get the impression they all think I'm crazy?