Rifaximin creates a few issues like allergic reaction in patients allergic to drugs like rifampin, rifabutin ( similar class of drugs)
There's nothing to worry unless you have clear established history of any side effects to these drugs.
Antibiotics are prescribed commonly for a time period of 14 days or more and are considered safe.
Next Steps
if it's concerning you enough , you may get done a few cheap blood tests like
liver function tests/
kidney function tests (
lft/kft) to asses your liver/kidney health while on this medication .
you may take an opinion if the values of those tests are abnormal.