strep after sucking dick

(:
i don't usually give blow jobs because i don't enjoy it and it doesn't give me pleasure. but i blew this guy and then him and i both got strep throats for the next week. (that was about 3 months ago) 
but now i'm dating this one guys and i sucked his dick for the first time yesterday and my throat started hurting again and i checked it and i have white bumps in the back of my throat again. why does this lee hapeneing?