What could this be? Every time I take any pain medication (lortab, tramadol, percocet,) I get bad chills, chest pains, shortness of breath, flank pain

Check vitals. Hard to say what is happening here. However, you want to check if you are having a drug reaction to the medications that you have described. This is like an allergic reaction.You can also check your blood pressure/ pulse.If your blood pressure drops too low, you can have some of these symptoms. Lortab /percocet are opiate type drugs which are known to have a tendency to drop blood pressures.