Right on my shoulder blade it’s so sore I’d call it pain not just an ache.
Haven’t used this trick in years but I’ve got a small hot water bottle hanging on a string in the cupboard. Fill it from the freshly boiled kettle & I can dangle it right over the spot.
Found a tape from the waist of some old joggers looped it through the string so it can go round my wrist & I don’t have to keep gripping it.