Alright, the odds of this being properly answered in a manner leading to treatment are slim to none, but here goes. I am a 19 year old male, and around the middle of summer, 2013, I moved from the Midwest to Hawaii for schooling. I stayed there for about a year, working in landscaping and mowing lawns in rather dirty conditions (possible cause?). Around the time that I moved back to the Midwest a year later, a rash had developed on my inner thighs, around the genitals, in the crux of both my knees, as patches wrapping along my hips, my armpits, and the crux of both elbows. This rash appeared gradually, spreading in chronological order to the previously listed areas.

Dominant features: red/darkened rash, causing extreme itchiness (particularly at night(will regard scabies possibility in a moment)), with skin becoming slightly inflamed in clusters that progress in random directions. No "scabies lines", but w/ certain areas developing red bumps that may or may not develop into a cluster of irritated skin. The thighs are the worst, with the most intense itchiness, followed in intensity by the genitals, backs of the knees, armpits, and hips.

Treatment attempts: Initially, I took the rash to be the result of friction in the areas irritating the skin, as I worked long days in the hot sun, moving constantly. The itching and rash progressed, however, regardless of maintaining a daily routine of showering and cleaning the areas. This prompted me to study possible cures, leading to the use of tea tree oil over the course of around 3 weeks, applied daily to each affected area. As this did seemingly nothing to stem the spread and severity of the issue, I simply resumed keeping everything clean to prevent infection due to the occasional gashes left by constant scratching of the areas.

Upon returning to the Midwest, I went to my doctor to obtain a diagnosis. After what was, in retrospect, a rushed glance at my genitals, thighs, and legs (no samples were taken), I was diagnosed with scabies, and given a 5% permethrin cream. I applied this on all surfaces of my body (to jest, all but eating it at this point to rid myself of this affliction) twice, waiting the prescribed two weeks each time... this, once again, produced no noticeable results. At this, a sort of desperation took hold, as I was unable to do a follow-up with my doctor. Thus, I tried various treatments, most of them centered around the theme of scabies treatment, including : topical Ivermectin application, neem oil, tea tree oil, vinegar application, and -most likely- several others.

Some other observations have been made since that time, most of them seeming to disprove the scabies diagnosis. First of all, there are no visible tunnels so commonly ascribed to scabies. Second, a sexual partner who I had during the initial stages of the rash (before my diagnosis by my doctor), with whom I have maintained very close contact for fear of them having acquired it as well, has shown no symptoms (rash,itchiness, etc.) over a year after we last made contact.

So now we come to the present. I am going to see my doctor once again this coming February, and the rash has remained in all of the aforementioned areas, though spreading seems to have ceased. Itching, while now accustomed to and lessened by experience, is nonetheless still rather severe, recently causing a bout of sleeplessness from night-time itchiness. I am far from miserable, but a lifestyle involving exertion often inflames the rash, something I could do without. Thus, I implore anyone here to consider something I may have myself missed. I will respond to any additional questions, and would be forever in the debt of whomever may crack this case.
edit: the image titled "photo", is one of my left hip, the likes of which is of interest due to its darker nature in comparison to the other areas.