Dear friend, welcome to HCM !
Are you on any medicines or blood thinners?
Is it warmer, itchy, elevated?
or just reddish, bluish bleed just below the skin?
Is your skin generally fragile?
Do you have any fever?
Such painless bruises occurring spontaneously are usually subcutaneous bleeds, especially if you are on aspirin
etc. Sometimes spontaneously in fragile skins.
Subtle clotting/ bleeding disorders may bleed like this.
Can you post a photo here using the site's uploader?
If it increases or new ones appear, you must see your doctor to evaluate for differentials.
Take care and please keep me informed of your progress.
Good Luck !
I hope to have answered your query satisfactorily.
May I request for your rating and review of this answer before you accept the answer and close the query (if there are no more follow up questions)?
Thank you !