Brief Answer:
Chondritis, hernia, GERD are possibilities...

Detailed Answer:
Hi.
Thanks for your query.
Noted the history and understood your concerns.
Noted that the pain is of pinching, shooting type - happened a few nights in the last couple of weeks - upper stomach to sternum - shoots up to the chest - weird feeling - get all of a sudden when this happens - sometimes quick stabbing pains in upper stomach ....
Since the problem has started a few weeks back and occurred a few nights without any other symptoms it is difficult to say with certainty the probable cause. As such symptoms do not fit into a known usual causes.
Well, the possible causes I can think about are as follows:
Can be severe GERD as it occurs at night.
can pain originating from the xiphisternum, that is the lower XXXXXXX part of sternum as chondritis.
Stress and anxiety also can cause such pains.
May be local myospasm of the abdominal wall muscles.
Small central hernia in epigastrium causing entrapment of fat.

This can be diagnosed by the following ways:
Get a clinical evaluation, an actual examination of the area, coughing tests to see for any hernia in epigastrium. May need high resolution ultrasound to see if there is any small hernia that may be difficult to palpate.
Local pressure on the xiphisternum can elicit tenderness if there is local inflammation.
Any relevant history related to acidity or GERD, the instigating or enhancing factors.
If suspected so, may need an upper GI Endoscopy to prove or rule out such possibilities. And other tests as may be advised after clinical evaluation.

All these things may help to get a probable diagnosis so that an appropriate management can be done.

I hope this answer helps you in getting the correct diagnosis as soon as possible.
Please feel free to ask for further relevant queries if you feel that there is a gap of communication.

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Brief Answer:
As detailed below.

Detailed Answer:
Cardiac reasons should obviously be ruled by EKG, Echocardiography and other investigations.
CT scan last Oct if normal is a good sign but the symptoms developed recently hence not of much help in present problems.
Pain of aneurysm is very severe and Ultrasonography of abdomen can show the abdominal part of aorta and Echo can show the throracic part.
Chondritis or costochondritis is usually aggravated by anything that gives strain on the lower chest wall or upper abdominal wall - like mopping, lifting anything heavy, stress and anxiety can add-on.
Investigations are necessary to rule out possible causes and is a part of diagnostic exercises.

I hope this answer helps you.
Please give feedback about the investigations done so far.
Wishing you early diagnosis and proper management.

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