Sounds like it's likely a hookworm infection. Check out treatment protocols for administering fenbendazole or albendazole over an extended period of time to treat. You can buy fenben from Thomas Labs (sold for fish) and make your own pill capsules using size 0 gel caps purchased on Amazon.
The situation is highly distressing and you're not likely to get a doctor to take you seriously. Stool testing often produces negative results for whatever reason, causing doctors to label you as delusional with no scientific proof of what you are experiencing. You are not alone and are in good company as you can see from the many posters on this site.
Take care of yourself and when things are overwhelming or you are in despair, focus on the very present moment, do grounding exercises, play some guided meditations on youtube and practice gratitude.