Sometimes when i stand up i get sudden pressure in my head, my heart beat is a little wonky and i feel dizzy. could this by my ms?

Not necessarily.: Your description raises concern of possible postural blood pressure drop, which could be a medication adverse reaction, but also, associated with a migrainous phenomenon. I do not see a medication to control your ms, only the steroids, which i presume are being used for a relapse. Would suggest starting a potent ms agent soon, and supplementing vitamin d. Have your doc assess all mentioned.