Need a Health Check

I think the severity of the pain has come to the point whereby I MUST go get a decent health check instead of going to a clinic for prescription only.

I have been having pain on the left side, near my chest area, under the armpit.
It started off as dull...
Took several deep breaths and the dull pain was gone...

Few days later, it came back.
then...
few hours later...

then now, the pain has gone from OCCASIONAL to THERE ALL THE TIME!

Today,
there are occasional sudden sharp pain on top of the consistent dull pain.

I have asked a medical friend and he said there are 3 possibilities:

1. Breast tumour
2. Posture
3. Stress

Whichever it is, none of them were what I expected.
I thought it might be related to the heart because my dad's side of the family have heart problems and my dad died of cardiac arrest.
So now, my horizon has widened...

Not going to think too much into it, tomorrow will be going for the full body check up early in the morning, so as to get my mind to rest and not have wild thoughts racing all over the place.....

*Fingers and Toes crossed*