Hello,
The urge of frequent urination can be due to diabetes mellitus. Other possibilities are glomerulonephritis, pyelonephritis(inflammation of the kidneys),urinary tract infection, hypercalcemia, hypokalemia(low potassium),hyperthyroidism, hyperparathyroidism, diuretic drugs and pregnancy.
In my opinion, investigations like kidney functions, blood sugar levels, ultrasound lower abdomen ,intravenous pyelography , pregnancy blood test, thyroid function tests and cystoscopy may be needed to confirm a diagnosis. I sincerely advise you to consult a urologist or nephrologist and get yourself evaluated so that a confirmatory diagnosis can be made. I’ll suggest consulting a urologist for the same and getting the uroflowmetry test done which actually tests the emptying of the urinary bladder.
I hope it helps. Take care and regards.
Have you ever had kidney stones. I had a probem just like that and it was a small kidney stone that got stuck.