Hi! As you have had severe bout of pain, and the pain is recurrent, it can not be overlooked as normal. Many times, ultrasound
or x-ray may not be able to detect few of the pathology which have not attained detectable size by ultrasound.
I would suggest either to go for a repeat CECT scan of your abdomen which is non invasive. If this is also inconclusive, then you have to consult a laparoscopic surgeon in your area for a diagnostic laparoscopy
, which can conclusively detect the problem and possibly it could be therapeutic also depending on the pathology detected. Wish you an early recovery.