Hi, Thanks for using HCM In My opinion you should stop worrying firstly. It is highly unlikely that you would have been infected through receiving oral sex. There is no evidence that HIV is transmitted this way, the primary reason being that saliva is not a fluid that transmits HIV. Furthermore, mouth ulcers are commonly experienced by people and are unlikely to be connected to the sexual encounter that you had. Get an HIV test at the 13 weeks mark just for a piece of mind, for now don t lose sleep over this. Take care as its the stress that has got you over .