I've never heard of an actual panic attack, which lasted for several days and included symptoms like "water hurts going down", so I'd say it's something else. Stress sounds plausible.
Most of these were probably suggested already, but I'll give a short list of things you might want to try anyway.
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Contacting your therapist/doctor, if you have any medications or history with mental issues. Maybe even if you don't - it wouldn't hurt to ask an expert what's wrong.
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Meditation, yoga, whatever helps you to relax and organize your thoughts and feelings. Maybe try to locate possible problems (physical or psychological) that could cause the symptoms.
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Going outside, maybe some exercising too (something enjoyable, preferably). I've heard a walk in the forests is supposed to be a good cure for stress.
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Healthier diet (especially under stress or while you have an upset stomach). Ditch the junk food for a couple of weeks - except the occasional treats of something delicious.
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Prepare well for whatever stressful event's happening soon.
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Remember to relax as well. Do things you enjoy doing.