The rash, is it near the injection site or all over? If all over, is it like small bumps?
I had a similar reaction (not from ATEC), but it turned out to be Isopropyl alcohol in the gear. Spent a night at the ER because of it.
I think i was told that it converts to Acetone in the blood and is excreted by the skin and in some cases can cause a rash or infection. I could taste it after injecting, it wasn't a metal taste like tren, it kind of tasted like nail polish remover smells... If that makes any sense.