Paranoia sometimes has this perceptions of conspiracy. Like him thinking you poisoned his lotion.Even if you want to help him,he may perceive some conspiracy. If you find out a local psychiatrist and suggest to him ,he may think you and another person (therapist) are conspiring to do harm to him.Specially he already has such thoughts about you.You wanting to help him out of compassion may further push him towards more paranoia. He doesn't trust you remember.I say staying away from him will do good for both of you.You said he is on a student visa.His school may have resources that he could use.If his condition is induced by his study stress,school will have a counselor available, I am sure.He needs to reach out for those resources available to him.