What causes dizziness,weakness and nausea?

Brief Answer: Low temp. Detailed Answer: I am sorry your son became ill in school today. Dizziness, weakness, and nausea are non-specific symptoms, meaning this list of possible diagnoses is long. However, at the very least it sounds as though he may be somewhat dehydrated. I wouldn't worry just yet about the temp of 85 degrees. School thermometers are notoriously inaccurate. You are already doing the best thing you can by taking him to the ER. Once there, expect them to place an IV and start giving him fluids. They will retake his temperature and do whatever is necessary to make him well, based on their reading and their exam. Good luck