Testing three weeks after rash

Hi all, i had a rash for a week at start of third week after condom broke with a thai csw vaginal sex . i tested after 5 weeks and got a negative result one week after rash had gone i tested on 7 weeks got a negative result. What i am wondering is if it was an ars rash should i have had detectable antibodies 3 weeks after rash had gone on an elisa test in uk gum clinic. thanks

[Teak]

It's possible for the body to not have produced enough antibodies for the test to detect. Test again at 12/13 weeks post exposure and the test will be conclusive.

[peekawho]

If you tested negative at 7 weeks, you should be very, very, very reassured.  If you are unable to accept anything less than 100% absolute certainty, test again later.