You developed severe back pain
while you were sitting on the floor, while you get up to sit in the sofa you got giddiness even after sitting in the sofa. You thought of going for walk to get fresh air, there also giddiness was not relieved.
After that within 2 days almost your giddiness is gone, where as you were not able to bend and you were not able to move your body either side even in lying posture. Now you are not able to bend even to tie your shoes and you also light headed which worries you.
Yesterday Your BP was 144/89
Too many questions from my side - what is your age, are you hypertensive, DM, IHD if so what are their control level.
For anybody sudden change position may produce giddiness. but you say back pain also which persists till now - needs MRI
lumbar and Cervical Spines.
Regarding light headedness- blood sugar, BP, ECG caotid doppler may be needed.
All the above conditions some how or other form a part of light headedness.
I have mentioned all possible reasons - you consult your dr,investigate and take treatment.