Welcome to the forum.
You had accurate replies on the HIV and STD community forums. You had a sexual experiece that carried little or no risk for any STD, and your symptoms are not those of any known STDs. Further, you had no evidence of STD after a professional evaluation, including negative tests for common STDs; and if you had been infected with any bacterial STD, the doxycycline treatment would have cleared it up.
Please read my reply in the following thread, which describes the biological reasons why exposures like yours carry no risk for STDs, including HIV:
http://www.medhelp.org/posts/show/1861534
To your specific questions:
1) You could not have acquired any STD.
2) You have no bacterial infection.
3) ARS does not cause symptoms like these.
4) I recommend no further STD testing at all. Your symptoms are typical of genitally focused anxiety due to a sexual experience that you obviously regret.
Really, you should stop worrying. You have no infection of any kind from the massage experience -- nothing that will ever harm you or any current or future sex partners. If you have a regular partner, you should continue to have unprotected sex with her (or him), without worry of any harm to either of you.
Best wishes-- HHH, MD