Parasite newly discovered - help

Hi everybody - I've been combing through these posts and assembled a lot of information but I'm getting overwhelmed and was hoping for some guidance. For background, I've been sick for years, everything from cancer to chronic pains to GI issues to sinus issues - the list goes on - and doctors haven't been able to figure out a cause. I went to a functional MD who tested for parasites & candida about a year ago but both came back negative. A few months ago I gained a lot of weight and my stomach became distended, but, I thought it was related to a change I made in a prescription I had been taking. Until yesterday... I went to the bathroom and found a 4-5 inch long "earth worm" like thing in the toilet. My husband got a bit freaked out and flushed it so I don't have a picture. So I'm now suspecting I have a parasite (and wondering if the weight gain may not be related to the drug after all).

I was going to take some magnesium citrate to "flush" things out then start on a combo Black-Walnut , Wormwood , clove. Is this the best course of action or should I try to get re-tested for parasites first? Is there anything else or something different I should be doing? Is there a specific brand I should try (trying to figure out brand and dosage is where I got overwhelmed). Do you think my chronic sinus pain could be related, and if so, what can I do about that?

Thank you so much for any guidance you can provide!!!