Why am I hot and dizzy?

I'm a 15 year old female. For a long time now I have been getting hot suddenly it lasts a few minutes then I'm cold, being in winter I thought this isn't right, but It wasn't until early morning yesterday, I couldn't sleep, I got suddenly hot and then I was sick constantly for about 5 minutes, then I felt dizzy, the sickness hasn't returned but the dizziness has, I have recently lost 2 very close relatives, I don't know if this is related but my doctor said it might be the cause of my sleeping issues, he didn't mention the dizziness or sickness or hot spells at all, I'm really worried, my mum thinks I'm a hypochondriac because I've been checking the symptoms for like everything, so I don't know who to go to. I have also lost appetite for everything, including drink. What could it be?