I am experiencing low back pain plus soreness in my legs and weakness of my body. what does this mean?

Body ache.: More information is needed to answer this question. But if I understood correctly, it seems that you are experiencing a condition commonly known as body ache. You might get body ache from a viral/bacterial infection or after an extremely physical activity. Sometimes, you can get body ache after taking certain medications. Daily body ache is generally caused by some underlined medical conditions.