I had anal sex and now have bad nausea. Is this normal, or did I get injured in the process? There has been no bleeding or vomiting as of yet.

Prob no injury. Anal sex may cause fissures which typically show up as pain and bleeding with bms so without these you are probably ok. Nausea is non-specific and probably unrelated, although if it continues, get checked. There is a remote risk of perforation, although very unlikely unless foreign bodies (eg. Sex toys) were involved. Std is also a risk, so see your healthcare provider if symptoms occur!