Why does my body ache constantly and I feel tired all the time?

Exam first. First see your physician for an exam and any diagnostic testing that is necessary, i.e. Lab work. If clear source of body pain associated with fatigue is not found consider these possibilities: fibromyalgia, chronic fatigue syndrome, stress, depression, sleep disorder.
Look at lifestyle. Look at how you are taking care of yourself. Limit junk food and eat a healthy diet. Exercise, even if you don't feel like it. Be sure you are getting adequate sleep at night. If this doesn't help, you should see a doctor.

Related Questions

Why does my body ache constantly and I feel tired all the time?

Possibilities. You need a full physical exam, routine labs, and a check by for fibromyalgia by someone who knows this illness. A lyme check and perhaps an anti-nuclear antibody might be worth considering. Whether there is such an entity as "chronic fatigue syndrome / encephalopathic myalgia" is a question i will leave for others. This is a fairly common and difficult problem; i hope a treatable cause is found. Read more...
Fatigue. This must be very disturbing and places a stress on life. These symptoms are so non-specific that from what you describe would need more info and an exam and possibly labs. Go and see your family doctor and get this worked out. Hope you get better soon. Read more...