Help with a friend? Dizzy, shaking, falling over, etc.?

Okay, a little info about my friend in case it helps. She's 18, underweight, on her period, and going through stress. Then again, her whole life has been stressful. Oh, and she has no insurance and is between jobs so she can't afford a doctor. I'm thinking I'll probably have to pay for her to go.

So we were hanging out at the mall yesterday. Everything was normal until she started to stumble a little. She was in heels so I thought nothing of it. She said she needed food so we went to the food court and got in line. While in line, she started to lean and stumble a little more so I had her sit down while I went to go get the food. She seemed fine for a little, but she starting doing it again not long after. She also looked like she was zoning out a little. After a couple more hours she got worse. She would just completely snap out of reality for a few seconds and practically fall over. I had to put my arm around her just to keep her upright. Eventually when we got to the parking lot I just carried her to the car. She insisted she was fine and that she wanted to keep hanging out so we went and got more food and went to Walmart and stuff. As the night went on she basically just got worse. She said she just wanted to go somewhere and relax so we agreed on a movie. Half the movie she kept dozing of and coming back. Then the part that worries me the most happened. She starting shaking. It seemed like a seizure, but not as bad as a normal one. I put my arm around her and that seemed to calm her down a little. I told her after the movie and she didn't even realize she was doing it. After the movie we went to Kmart because she just didn't want to go home, and left soon after because she was just a wreck. she couldn't walk on her on, constantly dozed off, and talked with slurred speech. I carried her to the car and started to bring her home. She still didn't want to go home so she told me to just drive around for a while. I figured, why not? As long as she's in a cushioned seat she should be fine. She fought dozing off for a while then eventually just passed out on me in my car. I drove around a little while she slept and then eventually just took her home. She woke up and got inside safely then texted me for a few more hours until she passed out again. She's hanging out with her friends again today and said she was feeling dizzy again so I told her to just go home, but she won't listen. She insists she's fine. I'm just worried about her, and like I said, she has no insurance or money to go to the doctor. Is there anybody who has any idea as to what may be going on?