Should doxycycline (100 mg) 2x daily for 2 weeks after that 1x daily for 3 weeks and again 2x daily for 2 weeks cure early secondary syphillys if it were present. my tpha and elisa test are negative and im taking doxy for dermatological problems?

These doses of doxycycline are 100% effective against syphilis. If you were taking doxy at the time of exposure, you could not have been infected with syphilis. If you started after exposure, it would have cured syphilis -- probably before syphilis blood tests would have become positive. Your negative blood tests are reliable and prove you were not infected; they do not need to be repeated.