I think I'm dissociating ever since my trip. Please anyone help. I'm desperate.

Hi guys, can anyone please help me or at least try to tell me if this is something serious. I (F17) felt a bit exhausted and anxious from everything about a week or two ago (regarding school and especially tests. I have high anxiety when it comes to tests). I came back from school and played some games and in middle of the game I started.. sort of dissociating. When I try to explain this feeling to someone, they get confused and don't understand, they think I'm crazy.

The best way I can explain it: it's like a panic attack,but not a full one. It's not like I'm not aware of my surroundings. I completely am. I'm fully aware of my thoughts. I even told myself over and over "oh my god am I dissociating". I try to calm myself down but it's like my head is trying to not be aware of it's surroundings. Perhaps it's like I'm about to pass out, but I know I'm not. Like my head is about to burst. Not in pain,but more like high pressure.

I went in a trip to Hungary. I spent my whole night in the bus in Friday, almost restless, had to walk the WHOLE day till 9pm around town. At about 8pm, all of a sudden my head started spinning in middle of me eating. I was hungry,but not that hungry to the point I was starving. After that I couldn't eat at all. I stood there and tried to calm myself down,then at some point same small "dissociating" feeling came. I tried not to worry my mom and talked about a movie series to try and get it out of my head. And then followed stomach cramps. We arrived home today at 5am, I slept and thought that was it but now everytime I stand up, sit for 10 minutes most the process starts all over again. It's worse when I look up or down. This also came randomly today ,even as I'm watching a show. It's like everytime I have a scared or exciding reaction it comes?? I'm not sure. Please, if any doctor can try helping I'd be very grateful. Just to note: I'm not on any medication, I don't have any allergies (that I know of).