welcome to hcm
that round thing could probably be a trigger point.
try frictional massage
over that point.
this technique uses thumb pressure in a circular manner over the lump ( trigger point)
this will dissolve the pain metabolites that hv accumulated in tat area.
also try icing that spot.
you can take analgesic
if pain is severe.
once the pain has gone down , try muscle strengthening exercises for trapezius muscle