Antibiotic advice for possible Ehrlichia canis infection needed.

Hoping there are some vets out there reading r/pets! My brother's dog came down with all of the symptoms of an ehrlichia infection a few weeks ago. He lives in Florida where the ticks that carry the disease are common. His vet put the dog on an antibiotic before any test results came back and he started to improve.

At this point I advised my brother to keep his dog on the antibiotic for the full month because the test for this disease frequently results in a false negative. This advice was based on research about tick-borne illness and antibiotic dosage that I had done when I had lyme disease two years ago.

I just found out that four days ago his vet called to report that none of the tests were positive and told him that he could take the dog off the antibiotic. So my brother listened to the vet rather than my advice.

Now, however, he is worried that I might be right and he wants to know if it would be okay to put his dog back on the antibiotics five days after taking him off. He has a whole month's supply because that's what was originally prescribed. Any vets know if putting him back on would cause problems? Thanks in advance!