I get dizzy spells !!?

iv had this for about a year now cuz i thought it was goin but it keeps commin back!the dizzyness i get is hard to explain its not like the whole room is spining round . its like im not there. like im in adifferent world even though i can see fine! really weird!im always tired and av hardly any enrgy not like most teenagers,.it happened when i was shopping about twice .and now i neva go shoppin cuz i hate to av it again . alot of things im scared todo now like go out to : eat dinner out,shopping,crouded rooms. but its even happened at home on my own befor.i was thinking i cud av anaemia.. but i dont no..so i went to the doctors & he checked my blood pressure . & i hated it so my heart started racin & i think my pulse dropped!so he gave me some tablets called beata blocker /Atenalol.he said come back in 2 weeks so im goin tomorrow but im scared of avin ma blood pressure again ! im scared il faint i almost did last time ..& right now i feel very lightheaded & faint since i took atenalol