Psychiatric. Hard. please advice me!

Hi, you seem to be having mood swings according to what you have written. This may be Bipolar disorder in which you have periods of extreme enthusiasm, decreased sleep followed by periods of extreme despondency or feeling helpless or hopeless. This needs proper evaluation by a Psychiatrist. Is your hypothyroidism in  control? Please check  if your T3, T4 and TSH levels are within normal range. Currently, you seem stressed by the upcoming exam. You can continue Yoga, breathing techniques that you already know. Fix a time for study, visualise that you are doing well in the exam to keep yourself motivated.  Think of how you had done well in the past and affirm daily to yourself that it is possible to overcome this. Eat healthy , protein rich foods, get good amount of sleep and some physical exercise daily. See a Psychiatrist as soon as possible. All the best!