To test the puffiness theory, you could try an antihistamine like Benadryl. Ask the doctor or look it up online first so you won't run afoul of any drug interactions.
I'd try one of the kind that has s smooth plastic applicator, and I would go see the ob/gyn and make sure nothing is going on besides some puffiness. It could be a lost tampon and it's irritating your vagina. You could also see if the doctor has ever heard of this kind of side effect of Accutane.
I take my medicine at about 7 in the morning btw. I just hate that I can’t use tampons sometimes :(