So, I take it you did dump it? IF not see my earlier post. It might improve. Worth a shot.
Thermocouplers sanitized and IN the fermenter are probably best(I"ve never done that), on the outside is also reasonable(what I do with my lagers in my fermigerator)....especially if foam/insulation material is used to shield it some from ambient air. For ales, I use a couple of huge Home Depot orange coolers(not blue or red ) to house the carboys surrounded with ice /water to reach low 60's or whatever ale temp I'm looking for... I use a standard analog dial thermometer with the stem in the water. Not perfect, but if the water is 62 degrees, the fermenter core is not 85*.
Still not sure we have your problem figured out....brew again and soon with mitigation of temperature and quality brew water and lets hope for the best.