can anxiety last 24/7 ?

Hi, welcome to the ehealth forum and I am glad to help you.
Your history and symptoms are pointing towards clinical depression and panic disorder (PD).
PD sufferers usually have a series of intense episodes of extreme anxiety during panic attacks. There is no single cause for panic disorder
Cognitive behavioural therapy is the treatment alongwith medication.A patient with depression, adherence to the antidepressant medications is the mainstay of therapy. 40% of primary care patients with depression drop out of treatment and discontinue medication if symptomatic improvement is not seen within a month unless additional support is provided in the form of psychotherapy.
You must consult a psychiatrist for the proper diagnosis and further treatment. For you, compliance to medication is important for which you can increase intensity and frequency of visits, read supplemental educational materials and discuss any side effects of the medication that you may be experiencing with your psychiatrist.
You can use deep breathing, exercise, remember all the positive events in your life as if you are daydreaming as the stress busters to cheer yourself up.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.