As long as the medication is not an extended release form you may crush it and swallow it with water. If it is a capsule form you can take the powder or granules out and swallow it with water.
I am not sure why but just guessing it might interfere with the genital's production of testosterone.
I would recommend taking Tylenol or ibuprofen for the pain. They are non narcotic pain medications.
It should start working within 24-48 hours and you should start feeling better, but you do have to continue the therapy for 10 days.
There is sometimes a difference between the brand name drug and its generic version. Sometimes the generic may not work as well as the brand name in certain people. It is not uncommon now for generics to be made outside of the United States. Many generic companies are now located out of the country.
Flucloxacillin can be used to treat strep throat, but I would recommend seeing a doctor first to determine if you have a bacterial infection or not before taking the flucloxacillin.