What Causes Small Pimples Developed Sporadically On Upper Body?

Age 49 male - caucasian (very light skin) has small pimples developed (in last two weeks or so) sporadically over upper body (mostly on upper chest and arms) and some on lower legs. Gets sun for one hour each Sat and Sunday (with 70 spf all over body). When getting sun covers self in t-shirt and towels all over body as had too much sun until approximately age 42. Has mild eczema. Also has mild rosacea