What could cause persistent rash and itch after sandfly bites?

I know how frustrating it is to face the issue of persistent acne. There is no real evidence that skin gets resistant to topical products but obviously anecdotal accounts would suggest otherwise. To cut it short, it sounds like you might need some oral medications like doxycycline or isotretinoin to improve the acute flares first, while using a appropriate skin regimen. From personal experience myself, when facing a flare we tend to overdo things, be it using OXY 10 five times a day and having chemical burns, or washing our face 10 times a day.

Thanks for the very clear history and photographs. The red rash looks like a bruise and this is likely to be due to excessive pressure over the area, aggravated by the compression from the stripes which squeezes the enclosed areas. This will typically take 1 to 2 weeks to resolve. Blood tests are usually done to rule out underlying conditions like low platelets which may lead to increased susceptibilty to bleeding. I assume these tests were done and were normal. I would suggest wearing leotards without this stripe pattern so that there will not be added pressure to the skin.