how do you know where to go and where not to go? We usually walk through a park near my house as he loves running through the grass… what do you mean clean up our back yard?
The first thing you need to do is find out what he has. No point in getting excited until you know what you are dealing with. Your vet will probably have some suggestions, and in any case, as I said, "google" is your friend. Once you know what parasite or parasites you are dealing with, cleaning up areas that you control should be possible, e.g. hookworm larvae are destroyed by sunlight, so keep the grass short in your yard and try to make the "pooping" area in a sunny spot! (keep the poop cleaned up, obviously). Ongoing, you need to keep testing his feces until he tests negative, and even then, I would check periodically since it seems likely he is getting reinfected (and false negatives are fairly common). Don't panic! You will get this sorted.