Updated Answer
I am not a doctor.
Don't take iron pills unless you have had a medical examination to validate it. Iron toxicity can be very serious, damaging the gut as well as the liver.
The safest way to get iron is to cook in an iron skillet.
What is the name of the "antacid' pills, it would be strange if they did not have a label, unless your in a clinical trial and did not know it. Find out what they are and include this information.
Get yourself a book on "Human Anatomy and Physiology", Barron's has a well written text in their EZ way series. Amazon.com also has older used editions of college and medical textbooks of physiology for cheap. I would not worry too much trying to memorize details of anatomy rather focus on the physiology aspects. This makes it easier to understand medical texts. (Word of warning: there is a great bias to promote drugs in the medical literature, so don't believe everything you read, use common sense based on your understanding of the human body).
http://www.merckmanuals.com/professional/injuries_poisoning/poisoning/iron_poisoning.html#v1119341
PANTOPRAZOLE SODIUM suppress the ability of the stomach to secrete acid (see FDA link below).
It would take a medical doctor to find out the true cause. The FDA pdf file below does list two things which might be the cause of your troubles:
The drug increases Gastrin levels and is dose dependent, one of the things Gastrin does is increase insulin secretion, and insulin lowers blood sugar levels, the body responds to low sugar levels by secreting epinephrine which moves sugar out of its storage sites in the liver but it also causes palpitations. Caffeine also can cause palpitations as well as missing meals.
The other thing is post marking information listed rhabdomyolysis as side effect, that is where the muscle cells fall apart leaking their contents into the body. Besides pain, the myoglobin stored in the muscle can show up in the urine. This would be one specific test your doctor could run, if it shows up then it should be reported to the FDA, as its possibility as a side effect is still under question.
Pepcid, is an acid reducer that available as a generic for cheap at the Dollar General stores does not have the side effect risks of the more powerful proton pump inhibitors that you are taking and has been on the market much longer, so there are fewer surprises.
http://www.accessdata.fda.gov/drugsatfda_docs/label/2012/020987s043,022020s006lbl.pdf