Hal, sorry to hear it but hopefully it will be a short illness. Since you are vaxxed and boosted the chances are that this will not require hospitalization or other intervention like Paxlovid
https://www.yalemedicine.org/news/13-things-to-know-paxlovid-covid-19 Note that if it seems "bad" you should call your doc and get the pills. - or maybe just call him/her anyway and see what they say.
My wife caught this recently while we were on a trip overseas. She tested positive at the cruise port so we were denied boarding and spent 6 nights quarantined in a (nice) hotel. Like you, she tested negative one day earlier but then was positive. Fortunately, her illness was like a mild cold and passed quickly.
Good luck and let us know how you do.
Jim