Mastitis lingering fever

Me again, asking about mastitis. I’ve been in contact with the nurse at my OB and I’ve been to the ER twice over worrying over this. Here’s my thing I started my antibiotics this past Friday, it Is Wednesday and since Monday I’ve been running a low grade fever 98.9-99.3... every once in a while my temp will be normal. Probably more times than not, but I get the occasional reading of low grade. My dr and the ER said that’s not a fever and that my antibiotic is working because my breast is no longer red and my temp isn’t what it was (101.8) I guess my question is... has this happened to anyone else? Is this a fever? My normal temp is 97-98.6 so obviously it’s still elevated... the ER said there’s no abscess and to continue the antibiotic I was prescribed. I’m just worried about it, because I feel like the fever should be gone completely. Advice please?