Hi.
Anal sex doesn't cause nausea; however, your digestive tract may have been upset by the pain you experienced.
There are two issues here: the first is that you should never put anything in your vagina that has first been in the anus (fingers, toys, penises, etc.) without using a new condom, because the bacteria that live in the anus can be harmful to the vaginal environment, which can cause various unpleasant side effects like yeast infections.
The second issue is doing ANY kind of insertive sex without using a condom. It's important to remember that the anus is a very tight orifice, and tears easily, leaving it vulnerable to infection, so BE SURE to use a condom to protect both you and your partner. Also be sure to let your partner know whether you'd like to try anal sex in the future. It's important to communicate your preferences to him. Many women find it pleasurable, and it need not be painful, if you follow some simple guidelines. Dr. J
Not deadly, but at the veryleast you probably have a vaginal infection. I take it no condom was used in either case?
Thank you for your advice and knowledge, Sincerely Papichi