HI and welcome to HCM. Thanks for posting your query here. The pain in between the pelvis and rib cage
and changing with posture and on the left side resembles to be renal colic
. Renal colic is a condition where there stones in the urinary tract
. The stone could be in kidney
or along the ureteric pathway like ureter and its joining with the bladder.
The other condition to rule out could be pancreatitis
, especially if you are alcoholic. But in this condition the pain will be too severe and doesnt change with positions.
It will be helpful to get an x-ray KUB (kidney, ureter, bladder). This will be more accurate. Untill then you can manage with simple analgesics. If possible get the urine check and renal parameters check.
If it is a kidney stone the treatment depends on the size and site of the stone. Treatment ranges from taking more fluids to removal of stone by simple modern techniques.
In the mean time take more fluids and get an appointment. I hope this is helpful to you. Any further doubts you are welcome.