Hi welcome to Health care magic forum. Most possible thing is arthritis
of left sacroiliac joint
. other possibilities are reno lithiosis with stone at the junction of ureter
and bladder, or urinary tract infection
. I advise you to consult a urologist
for diagnosis and treatment. You may have to undergo MRI
for confermation besides other routine tests.
I advise some diet recommendations for relief of symptoms as Avoid taking potato, other tubers, tomato, egg, fish, other sea foods, to avoid orthopedic pain.
Take more of green leafy vegetables, pulses, sprouts, milk, fruits, juices, and dry fruits to improve blood, general health, resistance, and stamina to withstand such pains before they are cured. Wishing for a quick recovery and thanks for calling.