Intra-abdominal Pain: infection or obstruction of a hollow viscous
e.g. appendicitis, Gallstones, obstruction includes twisted gut (volvulus) also:

Vascular disorders such as Infarction (occluded blood supply to organ) and aneurysm (ballooned-out wall of the Aorta ruptures).

Extra-abdominal Pain: sources include thorax(chest) abdominal wall and
pelvic cavity.

Metabolic: diabetic ketoacidosis, systemic lupus, sickle cell disease

Neurogenic: herpes zoster (shingles); degenerative disc disease* (DDD);

*may cause pain around the abdomen, as can various spinal conditions.

CHRONIC ABDOMINAL PAIN:

Pain may arise from a variety of conditions, which are discussed in this article.

There may also be referred pain from other areas such as the spine, the chest or the pelvis.

It is not possible to explore each and every possibility in an article such as this.

There is, however, one point that is of great relevance to those with chronic pain of any type: if there is centralisation of the pain, (which may arise regardless of the source) there may be a range of abnormal sensations affecting the whole body rather than just the original area.

These may include what is termed allodynia, which is increased sensitivity to stimuli which would normally be painless, such as light touch, so that these provoke severe and continuing pain, usually burning in nature.

There may also be an hyperpathia, which means heightened perception of pain: however, this is not to imply a low pain threshold; in fact, the reverse is the case, there is an increased threshold and a time-delay, but once the threshold is reached, there is a massive response, out of proportion to the stimulus.

This overblown response may result in bowel gas causing very painful
abdominal cramps, for instance.