ESR is increased in number of health conditions like infections, Autoimmune diseases, Tumors , pregnancy, Menstruation and the list goes on. It is not specific to a particular condition or disease.
It is interpreted along with other tests like
CRP, Autoimmune profile, basic blood panel etc, NOT to forget about your symptoms and clinical features.
Given you have ESR of 15. It is not significantly elevated.
Next Steps
Kindly provide detailed clinical history - symptoms, duration , areas involved, whether symptoms developed at once or over a period of time.
Don't be hesitant, feel free to ask in case of any doubt.