Thanks for posting your query at DoctorSpring.com
I have gone through your question in detail and I can understand what you are going through.
The condition that you are having is basically panic attacks. This is a disorder of anxiety and occurs cause of imbalance of certain neurotransmitters in the brain. especially serotonin, nor adrenaline, and dopamine to some extent. Medicines are the best options to take care of these symptoms. Paroxetine is the the most popular medicine and my drug of choice. I generally prescribe my patients 12.5 mg per day at night which takes care of anxiety symptoms. Also certain medicines like propranolol and clonazepam can be give as required when there is a panic episode or expected situation where panic attack can appear.
Taking alprazolam is a temporary relief from the symptoms and you should seek proper systematic treatment with paroxetine instead.
Now coming to your immediate problem, there are no over the counter medicines for stopping panic attack. But I can suggest that you can take a double dose of your alprazolam like 1mg of alprazolam if the symptoms are quite severe. Further if you can arrange , propranolol is a also a good drug for anxiety and can be taken in the dose of 40mg. The only contraindication is asthma and diabetes. Otherwise its a safe drug and can be taken along with alprazolam.
Hope this helps,
In case if you have any further query, do let me know.
Dr. Srikanth Reddy