This may be gross to the uninitiated

Any parasitologists out there?

I had a disappointing doctors visit today. We didn't find what we were looking for, something that may or may not still be present. I was hoping we would find clear evidence, making it easy to treat.
(A) organism + (B) medication= (C)elebrating life without an intestinal parasite.

For those who don't know me personally, or from whom I've had enough tact to withhold this detail, allow me to put it this way:

I finally unpacked my last souvenir from my years abroad.
Unpacked it from my butt!

(Cue laughtrack.)

There was a worm. I saw it. And then I flushed it. So now the question is: is it gone? I keep turning in samples that come back negative. I have taken some medication, but it may not have been a strong enough dose to kill ....it. The only way to be certain is to, um, eliminate the organism (ga, enough with the vagueness- it was a tapeworm. A fricking tapeworm.)...where was I? Eliminate the scolex or head, which is how those guys latch on to intestines.

That hasn't happened yet so I just don't have confidence. This is quite understandable, considering I played host for at least 3 years before I was clued in. There's no way to tell if the medication was strong enough without properly diagnosing the species of tapeworm. And yet nothing shows up in the samples. My doctor suggested that the earlier medications may have been effective, killed it, and then my body absorbed it/ it disintegrated pre-elimination. Yet, some possible symptoms persist: lethargy, skin problems, digestive issues.

At what point do I give up and pursue other possibilities for my symptoms? Or do I keep pushing and look for a third opinion? I WANT TO BE SURE THAT IT IS GONE.

Has anyone out there ever dealt with this issue?