What are these symptoms from?

I get head rushes (black blurries in my vision and light headedness) whenever I stand up from watching TV or playing on the computer. My hands and feet are constantly freezing, even when I put socks or slippers on. They aren't blue, or anything, just cold to the touch. They feel warm to me, but freezing to others. I also get very violent body shivers, which I can do on command and sometimes they just happen. My mom gets them randomly too, do does my older brother. It is only in my upper body though. It is very annoying because people are like, what was that? I is sudden, and violent, like a huge shiver! It is the middle of spring, but i get them year-round.I also frequently hiccup out of the blue, and I hadn't eaten or drunken anything too fast. I have done a bit of research and I believe that they are Myoclonic hiccups. My muscles sometimes twitch, don't know if that is relevant or not. I have had these symptoms for about 1-2 years now, but the head rushes are new. What is happening? Is this normal? OR is it something neurological?