Screen goes blank until you squeeze phone

Lately when turning on my phone or while using it the screen goes blank (kinda dark greyish) but the touch screen still seems to be active.

The only way to get the picture back is to hold both lower sides of the phone and press the phone from behind, this works with varying degrees of success.

I'm thinking that there is a loose connection inside but anyone had a similar problem or have any idea what could be the solution?

Cheers