What causes multiple (tiny) hematomas to form on the scrotum? no visible swelling, no discomfort, occasionally break open and bleed.

Here are some...: What described most likely represents the common occurrence of harmless scrotal angiokeratoma (of Fordyce), which usually carries no clinical significance and requires no active Rx. But if bothered mentally or physically, skillful us of laser or cautery will help. If still in doubt, seek evaluation for confirmation and counseling since right Dx is hard to come by with a direct look.