The ornamental design for a shouldermassager, as shown and described.
FIG. 1 is a perspective view of an ornamental design for a shoulder massager showing my new design;
FIG. 2 is another perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a right side elevation view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The broken lines in the figures are for environmental purpose only and form no part of the claimed design.
And shading and cross-hatching are not features of the design but are utilized to illustrate the surface contours of the shoulder massager in the drawings.