If you do the exercises and it stays painful several days then it is too much. The supraspinatus is 1 of 4 rotator cuff muscles or shoulder stabilizers and if there is any RTC injury/weakness the it will bang(nt PT approved nomenclature)the bony arch above it.
Upper ribs or cervical problems can mimic Sx but a good exam can rule these out or in
The suggestion you were given is reasonable to try. If it starts to get worse and worse STOP