I'm an 18 year old girl, in England, and my period is 3 days late, so I'm a little worried, but it's not always super on time, so usually it wouldn't be a big deal, but this feels different. I've been feeling really weird and dizzy since yesterday, as well as light headed and nauseous. My back started hurting Tuesday afternoon, and my tummy has been feeling kinda icky since yesterday, especially when I hold it in.