Without elaborating, I can just suggest some straightforward but always underestimated approaches in daily life that alleviate stress and anxiety.
Get enough sleep: at least 7-8 hours at night
Exercise regularly: at least 30-45min daily
Eat balanced and varied meals, avoid junk food, keep in low carbs in order to avoid insulin spikes (possible cause of moods swing)
Completely avoid alcohol, smoking, caffeine or other stimulants intake
Try different relaxation techniques: progressive muscle relaxation, body scan, breath focus, mindifulness meditation
Talk to someone: seek help from your friend, doctor, counsellor, psychologist, any family member. Sharing your issues with someone would help you to get solution for your issues and would give you confidence to stand up.
Well for me it used to be a very big problem, whenever things wouldn't go the way I planned them I'd get panic attacks and the shear level of anxiety I'd feel would be overwhelming sometimes. I literally used to get anxious over everything from my finances to my love life.
What changed everything was when I realised that I can't control everything and there's only so much that I can do as a human being. I realized that my anxiety stemmed from the fact that I felt the need to always be in control of every situation and when I decided that that's not possible, it all just faded away.
My advice to you would be to determine the root cause of your anxiety first, it's from there that you can determine just how to deal with it. If yours is anything like mine then coming to terms with the fact that everything won't go according to your plan is what'll help you the most.
I hope this helps.