What would cause lower back pain and abdominal pain?

== == Well, unless you're dead after writing the question, it's not an aneurysm.

A disk herniation at L4/5 can cause radiating pain both in the anterior and posterior (front and back) parts of the body. What it feels like is dull pain in the abdomen and groin area, with sharp pain in the lower back.

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== == Most likely is musculao-skeletal pain, BUT... If you're in middle-late group long-time smoker, it could be an abdominal aortic aneurysm. Otherwiase known as a dilation of the aorta in the mid-abdominal region... If this sounds like you, get to a doctor for evaluation ASAP...!!! He can do a CT or MRI [if physical exam suggests one of these...]