Have you had any blood tests? Like amoeba serogy test or other parasite serologies for example. That could at least rule out some types of parasites
Treatment wise depends what you have whether microscope or something like roundowrm, Tapeworms or flukes, etc
Can try a course of hulda Clark herb cleanse and see what type of stuff comes out or try a course of something like albendazole or praziquantel. Symptoms can also give clues about what you might have