It seems like you have had a number of tests but did the Drs do the tests for Celiac Disease (gluten intolerance)? If that panel of tests was negative then you could try following a strict gluten free diet for three months.
Just doing a parasite cleanse may not help you much. Look at the cleanses at the Liver Flush Support Forum - all the effective programs include a parasite program and other cleanses, too.
The usual lab exams for parasites are often negative even tho you carry parasites. Several labs , one is Metametrix Lab, do advanced testing and look for parasite dna. They also assess intestinal function and have a test for Celiac Disease.