My husband had surgery for Afib 2 yrs ago his pulse is 128 he has a headache and is running a low grade fever and bad backache. He also had angioplasty 21/2 yrs ago I checked his pulse he is not does not have an irregular heartbeat  YYYY@YYYY
The pulse you said is high though as you SY its regular, it means that it is what we call sinus tachycardia, which I believe is secondary YTO the fever and backache, which should be evaluated with relevant investigation for the cause of fever and backache. Something I may suggest is sonography of PUB for any urinary tract infection, kidney stone or varied causes. If backache persistent and severe a X-ray and preferably MRI spine lumber for rarer causes which may result in low grade fever with backache, if routine instigation as your GP may suggest are normal. However get an ECG done as many a time when the heart rate is fast as human someone can misdiagnose it to be regular.