HYG selling off doesn't tell you much about credit. It's got the rate move sitting inside it.
People see that chart dropping and start panicking about credit going crazy. But on a big move in yields it's going to fall whether or not credit is doing anything at all.
The quick fix is HYGH, the hedged version, which strips the rate part out. If HYGH is going nowhere while HYG drops, spreads aren't really widening and what you're looking at is the bond move.
That's what I've had on my screen through these bond moves, and it's been pretty quiet. I'm not sure how good HYG is as a credit barometer these days anyway, given what's in it.