Hello, You are having vertigo (the symptoms are due to an asymmetric dysfunction of the vestibular system in the inner ear) which can be as a result of many things: Fatigue, vitamin and minerals deficiency, low sugar, electrolytic disorder, lying on one side for too long, and possibility of an ENT disorder if symptoms become permanent. The nausea is a result of the dizziness which can trigger the vomiting reflex. If your symptoms are transitory and do not reoccur, then there is no call for concern i.e it simply means that you simply laid on one side for too long and now getting to change position triggered a positional vertigo. This could be triggered by lack of proper nutrition. You might be feeding well but not having essential nutrients that could support your sporting activities. If the dizziness becomes permanent then you need to meet your doctor/ENT specialist for further investigations as even an infection of the ENT system can cause vertigo. Hope this helps