Thanks for your query.Based on the facts that you have posted it appears that you have painful micturition after having sex for multiple times during a one day .
There is increase blood flow to entire Genito urinary system
during sexual intercourse.As you are having sex for 3-4 times in a day this could be the reason for getting hematuria
and pain while urinating.
Since it gets resolved itself without any treatment you may not think of other reason.
Please ensure to have sex with fixed intervals and try to minimise as much as you can to avoid getting problems in future.