Add new wounds group mechanic, that will replace concussion for several cases. Concussion which player receives after KO from certain sources are quite absurd, e.g. KO by leeches. In addition, concussion is too harsh for newbies, blocking development for a fair amount of time.
Bleeding:
A wound received after stinging or animal biting attacks, or KO from them. Converts into blood loss based on different circumstances: gauze limits blood loss, active moving and stamina utilization increases it. Should last few minutes-dozens of minutes to let you make preemptive actions for further wounds.
Blood loss:
Stacks up after bleeding or different sources causing blood losses e.g. bats bites or leeches.
Blood loss debuffs your stats as concussion does.
Additionally based on bloodletting medicines, blood loss can speed up your healing: being fed on healing level (and probably some other conditions) lets your blood loss heal and have a chance to heal other wounds with it.
Being in bad conditions such as hunger or high stamina utilization causes you anemia.
Anemia:
Anemia should have same stat lose affects as blood loss, but lasts longer and heals over time by itself. This would be same as concussion if you not take required actions.
How should it work?
This should replace concussion for some certain cases, letting you not to close game for next 8 hours, but instead take some actions in 20-30 mins and also let you a chance to heal other wounds you received with nuts and continue playing.
Blood loss/bleeding should be preferable wound for newbie sources of KO, while concussion should remain in place for KO caused by more advanced game mechanics such as mining, PvP, large animals.