my doctor says i'm syphillis infectious but everything else online says i'm not?

[barbrakean]

i recently had a full sti test. i told my doctor that i had syphillis in the past about 2015 and that i was told i would always test positive for syphillis. . she said no thats not true.so we did the test and of course i tested positive for syphillis. i did the penicilin injection simply to be on the safe side. about a month later my doctor calls me and tells me i should do 3 shots of penicilin because she thinks i might have late latent or early latent syphillis because when i was diagnosed at 2015  i didn't do any bloodwork to determine if i was cleared. despite the fact that i have absolutely NO SYMPTOMS and had multiple boyfriends since than and never heard anything about giving them anything. i did an injection again and after i left her office i asked her how long am i infectious for. she said 7 days after my 3rd injection. so i told my friend and she told me that if i have late stage syphillis i'm not infectious and that even if i had early late stage syphillis from the time i got the penicillian injection i shouldn't be infectious anymore. so i'm pretty pissed so when i confronted the doctor she pretty much refused to admit that im not infectious and than later on agreed that im not. but i don't know if she just said that to shut me up.so i thought i'd come on here and ask for confirmation.

[Joejoesmith]

You can test positive for up to three years after an infection. RPR's can determine old or new infections.