"It does become debilitating being addicted man (you know) and you can blame it on other things - My Stomach Hurts, I Had Chronic Back Pain For Three Years, ... The more stuff you do for pain, the more pain you have, and the more you need for the pain, and the more acute your pain becomes (you know)"
One of the consequences of severe pain is that the sufferer starts to focus on the pain itself, rather than the cause of the pain. The pain becomes objectified as the enemy, to be attacked by various forms of pain relief.
Pain relief may provide temporary respite from unremitting pain; but if the root cause of the pain is not dealt with, the sufferer becomes dependent upon the pain relief. Furthermore, the (objectified) pain relief becomes increasingly ineffective as the (objectified) pain fights back. Eventually the (objectified) pain relief itself becomes the problem. There are several feedback loops here, that serve to maintain or even amplify the suffering, as Kurt Cobain himself was painfully aware.
I'm worse at what I do best
And for this gift I feel blessed.
By the way, techniques such as hypnosis encourage the sufferer to objectify the pain, as a step towards pain management. See for example G. Edward Riley, "Hypnosis, Hypnotherapy, and Hypnotherapists", Find Counseling.com (formerly TherapistFinder.net) Mental Health Journal, April, 2001. See also Jean Jackson, "Chronic pain and the tension between the body as subject and object" in Thomas J. Csordas (ed), Embodiment and experience: the existential ground of culture and self. Cambridge University Press, 1994.