What type of arrhythmia can cause pounding heart/tachycardia and rapid breathing numerous times a day? it's really bad after eating.

Any one of: the tachy-dysrhythmias that are are coordinated enough to be functional. The only way to determine is by ECG which I would recommend be done today.

Many types : there are many types of arrhythmias that can cause that feeling. The best thing for you to do is see a doctor and have a holter monitor placed. That will give you a better idea of what's goong on.

Dr Fowler and another doctor agreed

Need examination: Taking into consideration what you have said of yourself under "conditions" with weight loss being part of that my guess is that something metabolic in your system is not right such as your thyroid gland or possibly your adrenal glands. I do not think this is an inherent arrhythmia of the heart or some type of tachycardic syndrome. You need to be worked up with blood, urine, & imaging studies

Dr Juchau and another doctor agreed

Holter: Pretty much any type a Holter should show what you have

Likely SVT: A variety of arrhythmias can do this but it is most like a supraventricular tachycardia caused by a release or hormones or surge after a large meal. If you have an otherwise normal heart (on echocardiogram), then it is not dangerous but can be treated with medications if need be.