Since you've had unprotected sex, it's possible that you have HIV - but the sore throat won't have anything to do with that.
The early signs of HIV infection are a flu-like symptoms that can appear as early as 2 weeks after intercourse (so not the same day or same week even). This comes about as your body puts up a fight against the virus.
Common symptoms during this phase are:
- Fever (high temperature)
- Sore throat
- Body rash
You may also suffer aches in your joints, tiredness, and muscle pain during this flu-like phase.
After this early stage, the virus shows no further symptoms for up to 10 years.
Although you did suffer a sore throat, you didn't mention any of the other symptoms. Also suffering a reaction on the same day you had sex would be very unlikely.
However, you can't know for sure (and your mind won't be completely at rest) until you take a blood test. In most countries this can be done at no/low cost and very discreetly - so I'd advise you do that.
