

Yeah see the doc, preferably one who works with people your age since this does sound like a somewhat amplified version of normal 18yo mood swings. The upswing sounds like so-called hypomania which is less intense and less dangerous than full-on mania (where you go mostly bonkers, spend all your money, and otherwise mess up your life). You may be able to work out behavioral coping strategies rather than suppressing it with drugs. But, again, see your MD, don’t listen to much to us Internet randos.
Sweet summer child.