I thought it might be because I have a much firmer mattress than I was used to. I put some folded fluffy quilts under the mattress cover hoping this would make the mattress seem softer - like my old pillow top. Didn't help one bit. My backache goes away eventually one I am up and moving about, but when I have it, it is like having electric jolts in my back until it resolves.
sounds like muscle spasms, I have them often because I have herniated discs in my lumbar region.. .. my discs became herniated ultimately due to a lot of heavy lifting some years ago.. so I would imagine your lower back muscles are protesting now because of the whole load of lifting over the last few weeks..
You need to be very careful...because your back may go into a serious spasm meaning you''ll be unable to walk due to the pain, until the back muscles relax which is extremely painful and can sometimes take days.
If you;re finding it worse in the mornings as you get out of bed, try the Alexander technique before you get out of bed.. it really does help...It was recommended to me by my physiotherapist years ago...
Before sitting up out of bed in the morning, lie flat on your back head resting on the pillow... legs straight and flat on the bed , arms flat by your sides ( you can do this on the sofa during the day if you feel the need ) ..gently draw your knees up together, feet flat on the bed, and sway your knees gently to the left as far as you can..hold for the count of 5.. and back up together to the middle again feet still flat on the bed.
Then with both knees together swing your legs gently to the right, count to 5 and back to the middle.
Do this 5 times each side , before laying on your side, and swinging your legs gently out of your bed slowly before the rest of your body follows.. always take your time getting out of bed when you have back pain...