Hi i am Dr Ahmed Aly thanks for using healthcaremagic site , I had gone through your question and understand your concerns .. In my point of view i think it is a side effect of the drug interaction or high prednisone levels may cause such tachycardia or arrhythmia of your cardiac muscles . Sometimes its a kind of allergy or hypersensitivity reaction but for my patients i may recommend further cardiac investigation under effort or by echo cardiography while having such attacks for proper diagnosis and management . I think you may need to ask your physician for re dosing or changing the treatment with such drugs . Please click and consider a 5 star rating with some positive feedback if the information was helpful. Wish you good health, Any further clarifications feel free to ask