To my knowledge, only the really serious cases need treatment. The blood retained both in the skin and in muscles, unless the bleeding didn't stop, is easily and painlessly absorbed. There are some instances where the blood clots and may need a lot of extra care, because then it is a ticking bomb. Fortunately those instances are rare and our bodies do a great job cleaning it up.
Notice that I am talking specifically of blunt force trauma applied to muscles or fat tissue, not bone or unprotected organs. Any other type of trauma has it's own set of issues and rules.
It should be mentioned that during the first fight with Erika's former "boyfriend", the MC only got so bruised because after being surprised by shove against the urinals where he got dizzy, he then received a few hard undefended kicks on his chest and arms. These are obviously Hematomas, and would disappear on their own without treatment, the intervention by Samantha only hurried it along by maybe one or 2 days.
Peace