Can bone/joint pain be the only symptom of leukemia a person has? What would the pain be like?

Unusual. It would be unusual not to have any other symptoms but bone/joint pains. Most folks will feel weak(due to anemia), have skin bruises from low platelets and often have infections due to low white cell count. A blood test called CBC can address your question better. If the blood test showed any abnormality, then a bone marrow examination may be indicated to confirm presence or absence of leukemia.