How do I prevent bringing home fleas from my vacation?

I went several states away to visit my grandmother for two weeks (a little over a week in right now) only to find out she has a rather terrible flea infestation, and she has four cats. We've finally got the medicine for the cats in the mail and treated them, they are doing fine for the most part, and we've been vacuuming EVERYTHING and washing sheets (some vacation huh) until she can get a spray or something to help, which won't be until after I leave.

As of now I stay in the only room the cats don't typically enter, and my suitcase and clothing are in this room. The issue being, one of the cats got in, and now I cannot sleep at night because I am being eaten alive (averaging about a dozen bites a night). I've resorted to getting up and putting rubbing alcohol over my skin to get them to stop.

For the last few days of my vacation I am staying in a hotel, coming back for the last night before my flight. We will then be washing all my clothes in hot water and immediately packing them. My concern is that I have two cats at home and definitely cannot afford to bring the fleas with me, I have no money and she will not buy anything to spray for fleas until her paycheck after I leave, and I am terrified that they will get on/in my luggage or are in her car and I really don't know how to combat it with no money.

I really need some help.