So, first. You didn't/ aren't taking PEP. You took Prep. There is a difference. One you take after an exposure to an hiv person that is deemed a risk and your doctor was very smart and told you accurately, you didn't have one and didn't need PEP. You don't/didn't. The only ways people get HIV is to have unprotected vaginal or anal intercourse or share IV drug needles to inject drugs. Oral isn't a risk protected sex with an intact condom isn't a risk, rimming is not a risk. So, you had no risk for HIV. Truveda is prophylactic medication. If this was prescribed for you by a physician, you should not take it. It is Prep, not PEP. They ONLY give it to those at risk of getting HIV because they have a regular HIV positive partner. It also takes about 20 days for truveda to begin providing protection with consistently taking it every day. You MUST be hiv negative confirmed prior to taking it. So, ya, that probably wasn't a great idea. This is why we leave medical care to doctors. The good news is you had no risk for HIV transmission though.
Oral is zero risk for hiv and you can't get hiv when you used a condom so you have nothing to worry about.
"I phoned up a UK helpline who said I didn't need pep." You should have listened to them and not self-medicated - "chance" has nothing to with your encounter. Therefore all of your hiv questions are irrelevant.
Millions of negative people like you get neck pains all the time. You will notice that when you look at the pain relief portion of the OTC portion of a pharmacy.