Just my two cents here, tigress, but if he's not responsive when you communicate how awful you felt, I'd dump his sorry ass.
In reading this thread, I realize now that I've experienced subdrop twice. Once from an onliner and once in r/l. Once immediately after and once the next day.
When I called the onliner, in near hysterics, he said, "I can't talk now, I'll call you later." (he was busy having coffee) Needless to say, when he called I told him to eff off and slammed the receiver in his ear. I never wanted to experience anything like that again - especially sans support.
In the r/l relationship, it had been the first time and was an intense five days (although it wasn't a BDSM relationship, more daddy/lg, it involved some of the kink, that I won't even allow myself to remember). When he left after five days I felt myself seriously dropping emotionally. And I truly thought it was just his absence at first. But it became a physical thing as well (i.e. shaking all over, feeling dizzy, a pounding headache, a racing heart - yeah, kinda like a panic attack)
When he called, I was still experiencing this and he was able to talk me through it - even though he had no idea what subdrop was.
So, yes, in retrospect, I do believe I've experienced subdrop - and it's damn scary. But, tigress, I don't think it'll kill you to go through it alone.