Hi!
That people can feel bad when they drink alcohol is nothing new or strange. This is normal. Alcohol can also trigger migraine attacks in many people.
Usually how sensitive you are to alcohol can differ from person to person and also depends on your weight and gender and how used you are to drinking for example.
I also have a more speculative answer to your question. Alcohol is a known vasodilator, meaning that it opens up your blood vessels, which can cause a drop in blood pressure. This in turn causes your heart rate to go up since your body tries to compensate and keep up the blood pressure. It is also common to get dizzy from low blood pressure. That your headache would get better when you lie down could also be explained by this since it is much easier for your body to keep the blood flow to your head (which is the important part) if you lie down than if you stand up.
So it could be a drop in blood pressure. This is usually very harmless. The risk is that you get so dizzy that you faint or otherwise fall and hurt yourself. You could also be a bit low on blood. You can go to your doctor and check your blood values and the blood pressure sitting down and standing up.
But all this is just speculations. Really, that your heart rate goes up, that you get dizzy and get a headache are all very common symptoms of alcohol effecting your body.
It is not uncommon for girls in your age to be little bit anemic (low on blood) so it can still be worth a visit to the doctor!
Take care!
Hi and welcome to the Migraines & Headaches Community.
I am not a drinker so, I honestly have no idea. Maybe someone else will come along that can help.