cats

This is Cleo. She is 2.5 years of age. I have posted about her before actually. I worry about her because she gets so anxious that it harms her. She has had an outbreak of hives on her skin, especially her ears, for the last week or so, and she has been picky about when and what she wants to eat, if at all. We got a kitten in June and she gets along with him, so I don't think that's the issue. Most of the time we find Cleo hiding and terrified of human contact, and we have to be very gentle with her. She does not like eating with her siblings. They were all born here in a stable, non-abusive environment by the way. Lately she has been bonding with me, but on her terms. Is this something that requires veterinary intervention?