My son went through this at around age 3, too. He wasn’t physically sick, and hadn’t been misbehaving either! He IS a very high energy, sensitive and "spirited" child, and we finally figured out that he was actually talking about being nervous or upset about something, but was keeping it inside and not really showing any outward signs of it. Sometimes it was about a new set of circumstances, or something else that was happening around him, that upset him (and not always something that WE would imagine should be upsetting! But it DID upset him). After we got this all figured out, we taught him to distinguish between being physically ill and being nervous about something. When he was smaller, he used to tell us that he felt "sick and sad inside"; now he just says that he feels "nervous", and is usually OK after a short quiet time (and/ or some hugs!) to get himself together. Maybe your daughter is trying to convey an emotional uneasiness, for some reason or another?? Hope it’s nothing, but an "attention getter"!