Unidentified parasite. Lab tests came back with no detections

Greetings,

I was wondering If you could help me determine if I have a parasite, and If so, if I can ask for anyone experience taking over the counter or nonhuman (dog/cat/cattle) drugs to cure such parasites.

I have seen transparent string like object in my stool since november. I went to my doctor and had to collect 8 separate samples, none of which came back with positive results for parasites. My doctor wants me to conduct another round of tests to confirm. I would normally agree but I spent nearly 300 dollars on the testing and am torn on spending more money for the same result as I cannot afford to keep testing. I wish I could just try a medicine and see if it worked instead, or have a doctor visually ID my concerns.

The images I have below is a very uniform looking tranparent string (potential parasite). It does not break very easily. Also in my stool are also strings that are very small radius and break apart very easily. I think those are more likely my imagination or mucus than the images I have below of the larger string.

Does anyone mind providing a bit of help?