Might have had a seizure?
So I was laying in bed, and had been on my phone for around an hour or two. I had to get up to talk with a family member, and as I stood I got the head-rush feeling you get when you stand up too quick, which is not terribly uncommon for me. However, as I was talking to my family member I lost awareness of the situation and started shaking/convulsing, but remained upright. I have no idea how long this lasted or at what point it started happening during the conversation, but after it was over I tried to play it off and continued the conversation. There have been no side effects, and it hasn't happened in the hour since. This has also never happened before. Any ideas on what caused this and what happened?