A tip my osteo gave me with my back (that often gets so stiff it goes into spasm - which is nice) - providing you're not preggers that is, or you'll be stuck like a beetle on its back:
lie on your back on the floor,
grab your knees and hug them t your chest to stretch your spine
rock gently back and forth still holding knees
THEN:
lie with knees up and back flat
relax both legs over to the right (still bent at knees) then over to the left, keeping legs togther
Do this about 10-15 times each side
Then rock again holding knees
Then carefully get up.
Works wonders for me, with lower and middle back pain.
BTW I am not an osteo so don't sue me if you do this too - it's just a gentle stretching exercise for your spine and hips.