Thank you for the query.
Left abdominal pain
can be caused by diverticulitis
(most common), urinary tract
infections, ovarian cyst
, inguinal hernia, large intestine polyps and colorectal cancer
. If this was CT without oral contrast and intestines clearing, diverticles might not be visible. That is why you should have colonoscopy performed. This will rule out all large intestines diseases.
If you find your pain more in the groin than abdomen, hernia is possible. A surgeon should examine you to rule it out.
Enlarged lymph nodes can be due to many reasons and the most common is infection or inflammation. It does not have to be a cancer. To make sure, lymph nodes can be taken for tests.
Hope this will help.