Why does my whole left side of my body ache?

Depends: I check your history page and it is blank. Are you male, female? How old are you? Do you have any medical problems? Do you have any other symptoms? When was your last physical exam? How long have the symptoms been occurring? What makes it better or worse? Have you been in an accident? Are you pregnant? Have you had a stroke? Do you take any medications? List them. Then i might have enough info.

Stroke: If you had a stroke this kind of pain is called "central" or "post-stroke pain". Otherwise there is no anatomical reason for pain in the whole left or right side.

ConsiderFibromyalgia: Typically, the fibromyalgia syndrome [fms] causes symmetrical chronic widespread aching and pain. See descriptions of fms in response to other questions above. However, about one third of people with fms experience pain which is more severe on one side than on the other side. Ask your primary care physician if you might have fms or see a rheumatologist with this question.

Doctor can examine: Normal, healthy people don't get aches without a reason, so if the entire left side of one's body ached, but the right side was fine, that would be very strange. A doctor would have to evaluate to see what might be wrong. Infections (flu, etc.) and auto-immune diseases can cause total body aches, but not just one-sided. Spinal cord and nerve problems can be one-sided.