how long do i take doxycline to cure my primary syphillis

[NathanEthicalVegetarian1988]

i am Nathan and i am a gay male. I been HIV positive and Undetectable since 2011. i get retested for my HIV results every 3-4 (so 3-4 times per year). When i went to go see my doctor and got my blood drawed i was called and told i had primary syphillis i had a 1:16 titer ration, when they drew my blood. Now i am allergic to penicillin so i was given Doxycline to take for 28 days (56 pills total or 1 pill every 12 hours so twice a day.) my Doxycline is 100mg. I started my Doxycline treatment approximately March 22nd and finished April 20th. my Doctor said to schedule to see her around May 20th to check my numbers. could i expect to be cured already or by the time i see my doctor around May 20th? also can you share more information on doxycline for those allergic to penicillin as myself so others can know about this? thanks for taking time to respond

[NathanEthicalVegetarian1988]

I took Doxycline for a month taking 100mg every 12 hours for 28 days ( i finished meds arounds April 20th) my doctor told me to get tested in a month so i got scheduled to get my titer ration checked on May 17th and my titer dropped down 1:8. My doctor scheduled to have me come back on June 13th . my ratio dropped from 1:8 to 1:4. So my Syphilis titer went down 2 fold. from everythng i have read and been told my syphilis is no cured. yay for me. glad to help present living proof to others reading this that if you are allergic to syphilis your doctor might /can prescribe Doxycline to cure you of syphilis if like me you have an allergic reaction to penicillin