While I'm not using excel or referring to the specifics of your question, you might consider tapping a live data feed for your state and county:
library(dplyr);library(ggplot2)
library(RCurl)
usa<-getURL("https://raw.githubusercontent.com/nytimes/covid-19-data/master/us-counties.csv")
usa<-read.csv(text=usa)
usa$date2<-as.Date(usa$date,format="%Y-%m-%d") # format date
usaS<-usa %>%
group_by(state,county,date2) %>%
summarise(cases=sum(cases), deaths=sum(deaths))
County Analyses
usaC<-usaS %>% filter(state=="California")
fcty<-c("Chico","Butte")
usaC %>% filter(county %in% fcty) %>% # subset in CA
filter(date2 > as.Date("2020-05-13")) %>% # filter by date
ggplot(., aes(date2,cases,fill=county)) +
geom_bar(stat='identity')+
theme_bw()