Brief Answer:
You will need an ECG, a clinical examination and some other investigations

Detailed Answer:
Hi.
Thanks for your query.
Read the history and understood it.

I would like to know a few more details for me to assist you more, please give feedback:
Since when have you got this pain, please specify hours/ days/ months ?
Any associated symptoms of chest pain, referred pain to the should or other area, sweating, pain in abdomen, nausea, vomiting, loose stools or any other which you may relate to the present problem?
Does the pain increase on movements of the abdomen, while sitting from lying down position, coughing or any strain on the abdominal wall ?

The most probable cause of the symptoms you have mentioned - pain 3 inches below rib cage on left side with a warm slight bulge - can be :
Colitis
Kidney bulge and infection
Local problem of the abdominal wall like cellulitis

I would advise you the following:
First of all get an ECG done to rule out any cardiac problem.
Consult a General surgeon or ER Doctor and insist for a clinical / physical examination of the area of the abdominal wall and the abdomen also. This helps in diagnosis as the hands of the Doctors can detect such thing that no other investigations can tell.
Get an ultrasonography of the abdominal wall , and the abdomen proper. This may give best idea about certain disease of the Kidney or so.
You may need a confirmatory CT scan of the abdomen.
Get blood, urine and stool tests done.

So the proper clinical examination by a Surgeon , investigations can lead to a proper diagnosis and plan for further treatment.

I hope this answer helps you to get a proper diagnosis , come out of the emergency and get a proper further treatment. Please feel free to ask for more or if you need further clarifications if you feel there is a gap of communication.

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