Did you end up getting a 28 day prescription? I think you were concerned about getting a 7 day prescription, which I agree is odd.
Just want to add that I am keeping you in my thoughts and prayers as I do with all those who are worried. Please keep us posted on how things are going. We are all pulling for you and are here if you need to talk.
You need to direct these questions to your doctor. There is a reason each drug was prescribed. If you are concerned about the length of the course you were prescribed (why you wrote in yesterday) or the regimen prescribed (what you're asking about today): talk to the doctor who prescribed these drugs or ask for a second opinion. Time is of the essence - PEP is not a sure shot, so you need to make sure you get it right to give you the best chance. This forum has no doctors and can't really help you beyond telling you to talk to a professional at this point.
Hope you come out of this OK.
Best.