Someone had athlete's foot about 1.5 months ago and was treated for it. 2 days ago he walked barefoot on my carpet. is the fungus on my carpet now?

No: It is fairly easy to tell if a person still has a problem with foot fungus..the skin is red and irritated. If the barefoot person has no evidence of fungus on his feet, I doubt any fungus was transferred to your carpet. But everybody going barefoot, and the moist environment, is the reason fungus is transmitted in bathrooms. I wouldn't worry about fungus in your carpet. Stay well:)