Hey Margy. Let me add to what MrToM has already stated.
The Healing Brush Tool utilizes two visual aids when in operation. The 'CIRCLE' is the brush. The 'CROSS' is the sample point.
Once you sample a target area, the Healing Brush Tool will only use THAT sampled area until the user (you) changes to a new sample target area.
Let me demonstrate. I have an image that has Pebbles on the right and just plain white on the left.
Here I have sampled the area on the right where the white cross is located.
The three "healed areas" on the left are the result of one single mouse click EACH.
Notice that I moved the brush of the Healing Brush Tool between mouse clicks. The Healing Brush Tool used the same sample target area for each mouse click.
However, If I click and drag the brush for the Healing Brush Tool, notice that the sample point will also move in tandem with the brush.
BUT..........if I click and drag on a different area without changing the sample point, the Healing Brush Tool still samples from that original sample point.
If you want the Healing Brush Tool to add neck instead of nose, you have to sample the neck.
If you want the sample point to track with the brush, you need to use the Clone Stamp Tool. After the first click of the Clone Stamp Tool, the sample point will track with the brush until a new sample point is selected.