Brief Answer:
Tests

Detailed Answer:
Sorry to learn about your bothersome symptoms.

It could be from the kidney such as a stone. However one needs to be certain as there are a number of other reasons for pain in that area such as a muscle pull.
When I see someone like you in my practice, I typically order the following blood tests in addition to a detailed physical examination:

CBC (Complete Blood Count, also known as Hemogram; includes Hemoglobin, WBC and Platelet counts)
Electrolytes (Sodium and Potassium in particular)
HbA1c (Glycosylated Hemoglobin = your last 3 months' glucose average). Also known by other names such as GlycoHemoglobin or Glycated Hemoglobin or A1c
Liver function tests (SGOT , SGPT, Albumin, Bilirubin, Alkaline Phosphatase)
Kidney function tests (BUN, Creatinine)
TSH (checks your thyroid) 12 hour Fasting Lipid profile
Urine albumin to Creatinine Ratio (early sign of diabetes affecting the kidney)
25 hydroxy Vitamin D levels (ideal range 40 to 60 ng/ml = 100 to 150 nmol/liter)
USG of the Abdomen (and a KUB : Kidney Ureter Bladder)
Correct diagnosis and treatment requires the opportunity to examine the patient so you must see an endocrinologist in-person.

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