Thanks for posting,
From the above presentation, the obvious thing is that you have a throat infection
due to two groups of bacteria the gram positive cocci (staph or strep) and gram negative cocci (e.g Neisseria gonorrhoeae
catarrhalis etc). The examples in bracket are the most like germs causing the throat pain. No significant growth within a few days does not imply much as culture can take several weeks (up to 2) to show any growth. The bacteria from swap could have been death during preparation for culture and so no growth will be noticed. The gram positive and negative cocci are often pathogenic when found in the throat(with conducive conditions can affect the throat, hence cause pain). Hence i suggest antibiotics to be started right away before the throat infection develops to a worst condition.
Hope this info is useful