Thank you for the query.
As CT scan
is performed when you lie down and not moving, the hernia
can be invisible for this test. Hernia usually appears while standing and pushing on the abdomen and in such condition the test should be done (groin ultrasound
Your symptoms seem to be caused by hernia which has recurred. Especially if your pain gets more intense while coughing or lifting heavy objects.
I suggest you to have groin ultrasound performed (even if CT were clear) and visit your doctor once again. Sometimes even if no hernia is visible, surgery might be helpful and should be considered in such case.
Hope this will help.