What Causes Sudden Stiffness In Legs?

Hi

My quetion is about stiff legs. Last night I slept poorly so Ive been drained all day. I woke up spining with very spotty vision. After work I went for groceries and my legs went partially stiif on me, I found it somewhat difficult and strange to walk. It was like my joints were seizing where my legs connect to my hips. It wasnt painfull just strange and it frightened me. I just kept walking and it went away after about 5 minutes. Im a 28 year old male and have never experienced this before. Any suggestions appreciated