Hey. Are there any other problems that seem unrelated? I think you should write down everything you wrote here, as well as anything else going on in your life that you think is unrelated, and go see your primary care provider. If they don't see an issue with anything, I would suggest asking for a referral to a therapist, psychologist, or psychiatrist. If you go see a mental healthcare provider, it would be beneficial to keep a log of your feelings for a week or from now until you see them, to track your mood and see if there are any outside factors triggering changes.
We wish you the best of luck. If you need any emotional support, we are more than happy to talk.
Nina