I'm 47 6'3" 325 lbs on bp meds, been feeling light headed, little dizzy, irritable, tired, sluggish. Was at wal mart stopped at bp machine 112/66 could I be experiencing hypotention?

Yes, that is quite low for your age group. Time for a visit to your doctor. Yes that is hypotension but may be a one time issue, but to be on the safe side, visit your doctor soon.

Mine is l28/60 and is normal for me on meds at 70.