Why do i have back aches all the time?

Need to be checked: Chronic back pain in younger individuals can be a symptom of serious conditions of the spine and other structures. I suggest you see a physician and be checked for inflammatory conditions of the spine, internal organs as well as mechanical causes of low back pain.

May be multiple : There are many potential reasons. Some like lack of exercise & obesity to an underlying spine problem like a spondylolisthesis that occurs in 6% of the population to rheumatologic issues like ankylosing spondylitis. This also could be pain from another region like kidney or gi. Get checked out.