I am not an expert, but I would definitely say that you are experiencing anxiety. This is not a mental illness, but rather an emotional disorder. If this is what it is, I would get a hold of it before it spirals out of control! It can lead to many problems like the nausea becoming diarrea, and the diarrea becoming IBS (a common disease in people withe severe anxiety.) It can also lead to becoming an agoraphobic. I have anxiety and have done a lot of research on the topic. It starts out like a feeling of nervesneous and feeling uncomfortable in your own skin. It can quickly become panic attacks. What your experiencing is very minor and that is why I say to get a hold of it!!! There is a book called panic to power, that can really help. If you just let yourself go with that weird, nausea feeling you are experiencing, instead of trying to figure out what is wrong with you, it will soon go away. Just talk to yourself and say I am just having anxiety and it will soon pass. Nobody has ever died from anxiety. It also helps to laugh at yourself. Just say hey, I am so into this chick, that she gives me butterflies in my stomach from just thinking about her. I would try these exercises because I am telling you from experience that you do not want this slight nausea to turn into something serious!