Simple Seizures causing lost of control of entire right side of my body

For the last 8 or 9 years I have been having an odd thing happen to me which I've learned to be a form of simple seizure. Many times when I stand up I will suddenly lose control of the entire right side of my body, it tenses up and it takes everything in me to just stand there and wait it out. They normally last like 5-15 seconds. I have no idea what is going on and doctors seem to be stumped as well. Im 25 and fairly healthy, no medical issues with the exception of a fairly minor case of Pectus excavatum. Last night I started feeling dizzy and it hasn't stopped yet, I'm not sure if that's related or not..