I had a new front door fitted and the door is now in the front external wall. the old door was set back 2feet or so from the external wall. above the old door and frame is some brickwork, i dont know what kind of wall it is ie load bearing etc, but there is a crack in line with the mortar about 1/2 inch wide at the side nearest the side external wall(if that makes sense)and at least 2/3 feet in length. I began panicking thinking the worst but there are no other cracks anywhere near this crack. I plan on installing a concrete lintel beneath the solidier course and filling the crack with either mortar or PU. what are your thoughts?