I don't know that particular theory, but I don't think it would really make sense to try and have a unified theory of disease, alternative or otherwise. (I don't think medical science really even tries to have one.)
Various diseases have such different causes that we cannot really expect to proscribe a common theory to them. The symptoms of cold are mostly caused by the immune reaction (and medical doctors also acknowledge that). Sometimes you may need to curb that immune reaction e.g. with antipyretic medication because the reaction could be disproportionately strong and be dangerous in and of itself; sometimes it may be best to just let it be. Sometimes it doesn't really matter one way or the other, and you could either take symptom-relieving medication to ease how you feel or elect not to.
(FWIW, I generally prefer not to take medication for a cold, partially because it doesn't help the healing -- in the case of cold, only time does -- and partially because artificially improving the symptoms might make you feel better than you actually are and thus make you believe you can already do more when you should still rest. So I kind of agree with you that people may take medication too lightly in some cases, but I certainly wouldn't treat all disease the same, because different disease are very different in many regards.)
In cancer, your own cells have begun to divide and grow uncontrollably. Normally cells have various kinds of built-in controls for growth and longevity; in cancer those controls have failed, and not just one of them but a number of them at once. Since there's always a nonzero probability of a mutation causing one of those mechanisms to fail, there's always a smaller but still nonzero probability of enough of them failing that the result is going to be a malignant tumor.
I fail to see why we should consider a tumorous growth as a reaction of the body trying to heal itself from something else. First of all, from what; and secondly, how would that even begin to accomplish the goal? On the other hand, the generally accepted understanding that it's just cells where enough things have wrong that they have gone into uncontrolled division and growth makes perfect sense.
Again, your immune system is going to (or at least should) react to that, but that's not what causes the disease, or perhaps not even most of the symptoms. (I lack the understanding to comment on how much of the immediate symptoms of cancer are caused by immune reaction, not to mention that cancer is again not a single consistent disease, but in any case, let's not pretend that cells that are nonfunctional and uncontrollably taking over space from your healthy tissue isn't going to be a disaster in most cases regardless of that.)
Also, many factors influence the risk of cancer, including nutrition. That's also undoubtedly true of many other diseases, and medical science agrees on that. (Different studies might come up with different results on what exactly those factors might be, but that's largely due to the complexity of the topic.) In some disease (e.g. cardiovascular) it might even be the most significant one.
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It's true that medicine traditionally focuses on treating disease, not on what generates wellness beyond that. I agree that there's a lot that can be achieved outside of medicine that can be beneficial for wellness (and even health).
It's also true that big pharma probably has an effect on doctors and their education. However, I don't think that makes medicine generally suspect. Rather, the truth is more nuanced and in between. Doctors, especially at major hospitals, have significant clinical experience in their fields, and that's not immediately affected by pharmacological research. Also, not all medical (or even all pharmacological) research is funded by the industry. Criticism of big pharma or even medical research is not without merit, but I think the impression I get from your comments is too cynical of the field.
While wellness is something where it's often best to listen to yourself, I would urge anyone with serious illness to seek medical treatment. That's certainly so at least in case of disease such as cancer which have well-established and evidence-based treatments.