Meaning of "medicine bringeth double care when the malady is past cure"

While I initially interpreted the phrase with a modern understanding of "care", as in to tend to, I did a check on the etymology of "care" to see if it could have possibly have another meaning and this is what I found on Etymonline.com:

care (n.) Old English caru, cearu "sorrow, anxiety, grief," also "burdens of mind; serious mental attention," from Proto-Germanic *karo (cf. Old Saxon kara "sorrow;" Old High German chara "wail, lament;" Gothic kara "sorrow, trouble, care;" German Karfreitag "Good Friday"), from PIE root *gar- "cry out, call, scream" (cf. Irish gairm "shout, cry, call;" see garrulous).

Based on the interpretation of care to mean anxiety, burdens of mind, I believe the 2nd half of the quote is saying that the medicine, though it "cares" for the wound, also brings worry and concern when applied too late.

"Search the wound while it is green" means probe the wound while it is fresh.

The entire sentence is simply saying that we should always examine the wound while it is still fresh: if we examine it when the sore has already festered, it would be too late. And I think it serves as a metaphor.

My previous attempt to interprete "the medicine bringeth double care when the malady is past cure" was that medicine would bring twice the happiness when disease can be cured by it. But after checking with EtymOnline (should have checked with it earlier), I realized, as suggested by Kristina Lopez, care is indeed a negative word in the past when it is used as a noun, and thus the correct way to interpret the sentence is:

medicine would have brought twice the anxiety or sorrow when the malady is past cure, or, when it can no longer be cured (in a way past cure).

I believe that medicine bringeth double care is using "care" in the sense of "a cause of worry or concern", so the phrase basically means You have twice as much to worry about: when you thought that the wound was minor, you only worried about how long it will take until you get better. Now that your neglect has caused a serious problem, you have to be concerned about surviving the treatment, living with a permanent affliction, etc.

My interpretation: When medication is started late in the disease process, it requires greater effort to treat ( hence double care ) when the disease has probably gone past cure (as a result of the delay). Something akin to "A stitch in time saves nine ".