I have been suffering flu-like symptoms for 5 days (chest congestion, severe cough, severe headache, along with overall body ache - especially as day progresses. Extreme fatigue even after sleeping. Went to Dr yesterday. Was not given exact diagnosis. However, was given Rocephan and steroid injections along with prescriptions for cough syrup and Z pack. When I picked up prescriptions was given correct cough syrup, as per prescription. But instead of Z pack I was given Amoxicillin 875 mg to be taken bid for 10 days. Is that an adequate substitution?