If I slept with someone who slept with a hooker and I tested negative on my STD test, should I get tested a second time because the accuracy of these tests is not 100%?

STI. yes you should as there is a lapse from being exposed to and before you show any signs or symptoms it is referred to as incubation period so if you got yourself tested the very next day then it may be negative safe sex use of condoms can reduce STI'S but even with a condom on you can still get genital warts syphilis and herpes as they are spread by skin to skin contact.
Repeat HIV 6m. You should repeat HIV test in 6 months. This is a high risk contact for HIV. Use condoms for protection!