Type 2 Splinter Hemorrhage under fingernails

Sometimes I get them too. The usual cause is mild trauma and sensitive skin under the nail bed. A more serious cause can be an infection of the heart lining (endocarditis) in susceptible people who have dodgy heart valves - Google it for more info. That's all I can think of. My nephew has a deformed heart valve and this is how I know this and he gets antibiotics before dental work.