Chimera Help

I'm working on an SF story in which the main character has long suffered from multiple odd health problems, including an autoimmune syndrome. He eventually discovers that he's a human chimera; a fusion of fraternal twins, one male and one female. Most if his cells are actually female, but enough in the right places are male for him to have developed anatomically as male. The complication is that the fusion was artificial. His mother is a biological researcher who, when she realized she was pregnant with twins, "did something" to get rid of the male. Only she fused them instead, and was very upset when she had a boy. Now, she's in an asylum (as you might guess, she was brilliant but unstable) and people are trying to unravel what she did.

What sort of autoimmune problems would someone like this have? What could his other health problems be? What sort of medications would he be on?

Suggestions on what the "something" the mother did would be appreciated.

What makes this SF is that the mother works for a company which has been making major breakthroughs by taking advantage of some alien technology the founders discovered. At one point I have the main character in a regeneration tank developed from bits of the alien tech.

Language Name

I'm working on a story set in an alternate universe where the empire established by Charles the Great lasted several centuries longer than in our world. As a result, much of western and central Europe speak a common language. Not French, not German, not Spanish, not Italian, but something related to all three. What would be a good name for this tongue?