Sharp stabbing pain

[content1]

I have been having sharp stabbing pain in the left side of my chest on and off for 2 years.
When it starts it last for a day or two, and if lay down it's so painful.
The doctor has done bloods & an ECG and it's gone back clear.
Anyone have any ideas what this could be?

No idea. Sorry to hear you're having trouble identifying it. Could it be muscular? When you have a flare-up, do you try stretching that side in various ways?