I Was Crying When It Happened But Was Walking Upstairs

i was crying when it happened but was walking upstairs and when i got to top i felt i was going into a asthma attack i had ringing in my ears too and blurred vison but this has happend before i was up in the air on a conveyer belt seperating recylcables and the guy infront me went blurry and i was getting very dizzy and shaky and ears were ringing then too. i stood up to walk and coouldnt almost collapsed.