I totally agree with John. There is no need to take the drastic step of amputation, especially if the real problem has never truly been addressed. parasite is defined as "any organism that grows, feeds, and is sheltered on or in a different organism while contributing nothing to the survival of its host". A scabies mite would fall into the category of a parasite. It burrows into the skin, lays its eggs and feeds off of its host. The perfectly round hole (blue/purple circle) on your finger, which I referenced in my first post to you, reminds me of a burrowing hole (much like that of a mole hole for example). From your pictures, it appears that the activity taking place on or in your finger is originating in the dermis layer of the skin. From my laymens eye, it looked like parasite activity where eggs had been hatched (the red circle).
The problem with prescription Antibiotics as a treatment for this is that they actually compound the problem by introducing yet another parasitic form, called candida (a yeastlike parasite or fungii). Candida will make its way to the weakest or most vulnerable area of the body and often has a reoccurring effect. Once a weak area has been established in the body, it becomes vulnerable to infestation or reoccurance of a flareup.
All that is said to say this, it's not that your case is hopeless (thus needing the drastic amputation); but rather, it has been (unfortunately for you) that your case may not have been properly diagnosed, resulting in treatment that was inadequate. Both John and Heather have given solutions or treatment options that I think are worth a try. In addition, and to address the candida problem as a result of Antibiotics , you will need to increase your fiber intake and consider implementing yogurt (containing acidophilus) in your diet. Both the fiber and the acidophilus (probiotic) will attack and flush out the candida. To help your immune system in the fight, you will want to implement a diet rich in the foods that contain beta carotene, zinc, and selenium. For further cleansing of the hand/finger, you may also want to try soaking your hand in a 15 minute Epsom Salt bath for approximately 3 days - 1 week. This will help in fighting the fungal infection. We tend to assume that the more expensive the treatment, the better it must be. You may be surprised at the results received by these simple, less expensive treatment options. Sometimes the answer is in simplicity.