Protected sex is safe sex and really not likely to spread any STI.
Condoms are obvious if they break.
Sex workers as a rule are low risk, they test regularly and look after themselves.
4-5 days is too quick for onset of these types of symptoms due to any STI.
Putting it all together I doubt you have caught anything other than the flu from your encounter and I urge you to relax, and get well.
For sure no HIV, wouldn’t transmit this way and it’s to soon for it to be showing these symptoms.
Theoretically it could be herpes. But without blisters anywhere on your body you can safely rule it out.
The most common cause for your symptoms are the common cold, covid19, influenza or several other respiratory illnesses.
Hope this helps. Please move on.