the collywobbles
noun [ plural ] UK informal uk/ˈkɒl.iˌwɒb.əlz/ us/ˈkɑː.liˌwɑː.əlz/
（由于紧张或略有不安而引起的）肚子疼
an uncomfortable feeling in the stomach caused by feelings of nervousness or slight fear
I've got the collywobbles about my exam this afternoon. 我担心今天下午的考试，肚子都不舒服了。