Back pain from last 3-4 months. Suggest.

I have backache from past 3-4 months but my pain got severe from past 1.5 months. I have got MRI done which suggests a slight disc bulge and some blood tests which suggests that I am vitamin D and vitamin B12 deficient. My pain area is basically the left side of my back, my lower back nd my spine. From last 1month I have been on bed rest so I could feel a little relief in pain but last week I had to travel for 2-3 hours but my condition got worsened. I had very bad pain in my back..even it was difficult for me to lie down on bed as I could feel pain in my spine,my lower back and the left side of my back nd the pain triggering to my left leg. If I am just taking rest , doing no sort of physical activity I feel relieved but as soon as I do some physical activity be it walking, travelling or sitting for even 20-25 mins without support, my pain again starts increasing. I feel very weak also. Please suggest.