Extra 3 symptoms and conditions

I had been on a prednisone dose pack (not too strong??) about a month ago for a neck injury to take away some inflammation. No side effects to mention and my neck felt tons better. Yesterday I went back to my dentist after 5 days of pain from a root canal. He put me on a prednisone dose pack saying there was some inflammation in the bone, very common, and the prednisone should take care of it. I took my dose yesterday, didn't sleep well (common side effect it seems) but then today my heart is racing and feels like it skips a beat. I have read this happening to folks on much higher doses, anyone have this kind of side effect with 20 mg/day?