Hi There, I Had Sex Two Weeks Ago, Then A

Hi there, i had sex two weeks ago, then a week ago with the same person, and am worried I may have an sti. A week after having intercourse I felt a slight itch so I put some coconut oil on it last night because it felt dry. Today I had a shower , washed the area , pat dry and put some candisan thrush cream on it. It stung a small bit for about 5-10 seconds but feels fine now.
How long after sex would you see signs of an std? And how do i differentiate ?