Thank you very much doctor, you have eased my mind quite a bit.
Welcome the the forum.
No STD can cause these symptoms only 2 days after exposure, and no STD causes such symptoms at any time. You caught a respiratory virus, perhaps influenza, perhaps H1N1 ("swine") flu. If not flu, probably it's just a more severe than average cold virus. It is possible you caught it from your sex partner, but it usually takes 3-5 days for flu or cold symptoms to start. The hot coffee is a coincidence; it did not cause any of this.
Influenza and colds are due to viruses and they do not respond to antibiotics. Do not take the azithromycin; it will not help at all. If your symptoms get more severe or if you want more definitive diagnosis, see a health care provider, then follow his or her advice about treatment. You can expect that s/he will agree there is no need for any antibiotic in this situation. (Indeed, one of the reasons why resistant bacteria are so common these days -- like MRSA staph you have read about, and also resistance in some STD bacteria -- is because too many people are given antibiotics when they are not needed.)
In any case, no STD is the cause of your symptoms. That part is clear.
Good luck-- HHH, MD