I'm looking for a manga where the main character is poisoned or injured by a relative or clan member, dies from it, but reincarnates into same body a couple months before he dies, and he goes hunting and searching for herbs while injured and manages to find or buy the herbs to heal himself and help his father get stronger as well. The start is similar to Eternal Reverence (Yong Heng Zhi Zun).
Maybe this is what you're looking for Isekai Tensei... Saretenee!
This story is about a teenage-boy who gets killed by accidently by God. So God decides he's going to reincarnate the boy into another world. But accidently reincarnates him into his old world with his old but new body and with spiritual powers. He can now see other people's spiritual moves and make them his own simply just by looking at the formula of the spiritual move and makes them far stronger than they originally was.