Clindessse 1 complete course

I saw my dr. today and I was diagnosed with bacterial vaginitis. She prescribed Clindessse vaginal cream 1 complete course for me. I am supposed to use it tonight before bed. My dr. also told me that after I do use use it my boyfriend and I should not have sex for a week. We had sex earlier this evening. I'm not really sure why she told me not to have vaginal sex after I use it? Does anyone know why? Is alright for me to go ahead and take it tonight before we go to sleep? I'm also a little nervous taking it. I read the patient instructions, and I'm happy that I only have to use it once and I don't have to mess with filling applicators with cream and stuff for days, but I'm afraid:( embarrassed. Can anyone help me:)