You're lucky that your doctor prescribed any parasite drugs at all for you. Most doctors usually diagnose patients with "Delusional Parasitosis" & prescribe anti-psychotic drugs as a cure, which, of course, is a big dose of "BS". (lol)
Regarding your Rx for 2 Biltricide (Praziquantel) tablets: Drug guides usually show low-dose, one-shot, or short-term treatment plans. However, medical studies show high failure & reinfection rates with those methods ~~ that IMHO wouldn't kill a piss ant. (lol)
But there's no need to panic. Tapeworm infections are not contagious. You get them from ingesting infected food or infected fleas. And the dosage you took might be sufficient if you had a mild infection!
If you pass another worm or show signs in your stools that you're still infected, ask your doctor to prescribe Biltricide (Praziquantel), 600mg, 2 tablets, taken daily, for 3 days. I would suggest a different dosage & longer treatment period, but your doctor may balk because it differs from drug guides, which most doctors totally rely on.
If your doctor refuses a new Rx based on your negative stool test, let me know before you start the tapeworm protocol. I posted it 4 yrs years ago & am not allowed to edit it with updates & changes. I've drafted a revised version but just haven't had time to finish & post it.