Brief Answer:
Hi

Detailed Answer:
Hello,
Thanks for your query.
I appreciate your efforts for medical consultation in so much distress.

Important aspects of your query are:
•     28 year old female
•     Known case of anxiety disorder, superficial gastritis and lumbar disc herniation
•     Complaints of: sleep problem, breathlessness during sleep, excessive thoughts, nervousness, craziness, anxiety, pressure feeling, tension in stomach, missing heartbeat, Palpitation and numbness in neck/arms/face/head.

Anxiety disorders can manifest not only with psychological symptoms but with a variety of physical symptoms also like: Tingling, numbness, hot and cold sensations, palpitation, chest heaviness, choking sensation with breathlessness, tremors (shakiness) and muscle spasm (tension in stomach, pain complaints) etc.

Your symptoms are more likely due to anxiety as you have:
-History of anxiety problem.
-Presence of several anxiety symptoms.
-Multiple physical symptoms not explained by one physical illness but can be explained by anxiety.

Although chances of having physical illness are less in your case but it is better to rule out respiratory problems and cardiac problems after examination and investigation by general physician.

There is need for treatment, if symptoms cause significant personal distress or affect personal/professional life (like in your case). Both drug and non drug treatment like cognitive behaviour therapy (form of psychotherapy) are used for treatment. Choice of treatment depends on severity of symptoms, personal preference and availability of treatment.

In drug treatment two types of medicine used. For immediate relief of anxiety benzodiazepines group of medicines are used and for long term relief most commonly SSRI (selective serotonin reuptake inhibitors) are used. SSRI takes around 3-4 weeks to show its effect. Non drug treatment like cognitive behaviour therapy (form of psychotherapy) also takes weeks to show its effect.

Apart from above advice following simple measures will help you:
-Decrease worrying by keeping yourself busy and distracted from worrisome thoughts by talking to family members or watching T.V. or counting back (100 to 0).
-Healthy diet: Milk and fruits in diet.
-Daily morning walk
-Follow structured daily routine. Fix sleep and wake up time.
-Do not use excessive caffeine (tea, coffee and cold drink)
-Stop substance use like alcohol (If present in your case)
-Breathing exercise, yoga and meditation (which you can learn from some nearby expert)

So take first step towards treatment and meet nearby psychiatrist. Usually patient show significant improvement within 2 weeks of treatment.

I hope this information has been both informative and helpful for you. In case of any doubt, I will be available for follow ups.
Wish you good health.
Regards,

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