I question the Tapeworm diagnosis, sounds like toxocara http://emedicine.medscape.com/article/229855-overview
to me based on the description. I don't think Vermox is the choice for Tapeworms anyhow, I believe it is praziquantel but you would have to research that. But I do think that Vermox is the choice for toxocara.
I am not sure if you stated the dose and duration, but it probably is not long enough to treat. Unfortunately doctors are not well versed on parasites so you might have to do a little digging. http://www.dpd.cdc.gov/dpdx/HTML/Para_Health.htm
No you are not going to die, just feel like it. Make sure you are amping up on nutritionals to keep your body strong and resistant.