. At 15, your body is going through dramatic changes. I therefore think your first stop is to your doctor for a complete checkup. Sometimes what you are describing is part of the body adjusting itself during adolescence. Sometimes there is a vitamin deficiency or something like a thyroid disorder contributing to the problem. I also hope you are getting adequate sleep. Sleep disorders can also cause the issues you describe.
If you check out okay physically, then it wouldn’t hurt to talk to a counselor. The Internet is a wonderful thing. Sometimes it helps people get a diagnosis and treatment early. But sometimes reading it makes people unnecessarily anxious about the possibility of having a disorder.
A trained counselor will be able to help you sort it out and decide if you are going through the very normal ups and downs of adolescence or if something else is going on. Either way, some therapy sessions might be helpful. Just because emotional instability is normal during the teen years doesn’t make it comfortable. It might be helpful to learn some new way to manage it.
I wish you well.