back spasms! post workout

i was dropped to the floor today by back spasms (never had them in my life).  i did a bunch of intense workouts this morning which really worked my lower back.  when the spasm**** i could barely breathe i was in so much pain.  i couldn't move and wanted to throw up.  my 4 year old son had to find my phone so i could call my husband.  

has this happened to anyone else?  how long should i wait to exercise again?  once i could move again, i took some pain medicine and a hot shower.  

Do you do any stretching that targets your lower back?  That would be what I'd do.  And ice.  Always ice.