Is it possible for hcg to fluctuate this much in a matter of hours?

Christy

I missed my period, so I took a clinicalguard hcg test yesterday afternoon. It showed a faint positive so I took a few more. All definite postitves. A few hours later I took a few more clinicalguards and all completely negative, though a frer had a faint positive. This morning everything's negative. Could hcg have dropped that fast?? No period yet, but I assume this isn't a good sign....