My boyfriend has a canker sore under his tongue and panicked sending both his mother and I pics asking what it was. Both of us said it’s a blister he got from eating or brushing his teeth too hard. Today he panicked, saying his mouth still hurts and asked if I’m cheating or seeing someone else I said no and explained the difference between a canker sore and “chancres” which is Syphilis. Cankers are from food/brushing too hard, and chancres are a STD that you get on penis or vagina or lip.. not under the tongue. Then he says that he thought it was an STD because his friend says it comes from sucking dick or kissing other people. I’m offended because he automatically believed what his friend told him instead of looking up the information first. He said I love you and I’m sorry but this is the second time he’s tried to make it seem like it came from me or that I sleep around. How would you handle this?