Suggest Treatment For Dizziness While Walking Or Standing Up

I m catching dizzy spells when I m walking r standing I fell as if I wold faint r fall if I dont hold on to something these dizzy spells last for about 2-5seconds n sometime s it comes back to back and its very embarrassing when people are around ..I do take high blood pressure pills but I have been out of my pills for 2 days and I haven t slept for 2 days whats going on?