After three days of swiftly flowing water, the bathroom clog came back...and so did Steve, my new plumber. Again, the drains stopped flowing late in the evening...on Tuesday this time. I called Steve Wednesday and he added me to his workday list. He arrived about seven pm, had things flowing smoothly in an hour and didn't charge me a cent. He said the clog was further down in the line than before and that if it comes back it may indicate a more serious problem...perhaps in the pipe construction.
I'm just going to keep flushing and hope for the best.