Happened to me 2 years ago.
it was so painful i laid in bed for 4 days unable to walk,stand,sleep, or even crawl. It was horribly painful.
I did not consult a doctor as it was impossible for me to move more than room-toilet and back!
But i did have lot's of time for internet research so I self diagnosed lumbago, violent muscle contraction of the lower back. Took me 4 days to stand/walk, 1 week to get back to work, 1 month to ride MTB.
I am quite stiff still, need some good streching every morning and every evening.
Hope you have an easier recovery but no worries, it does go away and you'll ride again