Start with the test from Metametrix (GI Effects Stool Test). That will give you the starting place. Treatment for each pathogen group (yeast, bacteria, parasite worms, parasite protozoa and parasite flukes) will all require a different treatment protocol. So there is no sense in trying to treat when you don't know what to treat.
If and when you get the test results, PM me and I can help you tailor a treatment protocol. I would suspect that since you traveled overseas protozoa may be some of the problem. Also because of the parasites you probably have a dybiosis situation going on.