My guess is that it's anxiety, for a few reasons.
One, you used a condom, which totally protects you against some infections and offers significant protection against others.
When you are busy, you don't notice the symptoms. That screams anxiety to me.
You mention a warm/cold feeling. There is no STD that gives this symptom, but it's a common one that people with anxiety mention.
However, you mention pain with ejaculation and frequency of urination. If you're well hydrated, and still having these symptoms, you may have a urinary tract infection (not at all related to sex), or a prostate infection (can be related to an STD, but isn't always - in your case, it wouldn't be, since the infections that cause it are prevented when wearing a condom).
If these symptoms are lingering, get them checked. Lay off alcohol and caffeine for a few days, as these irritate the bladder and are dehydrating, drink plenty of water, and see how you feel.
Speaking from someone who has experienced very similar things on a few occasions that you are experiencing now, it’s your anxiety vs any STD. As strange as it may sound, typically a sex worker is safer than a random hookup because they tend to test regularly and be safer unless she’s a druggie. You can go to stdcheck.com and go to a local lab with results in 24 hours to ease your mind although based on your story, you have nothing to worry about. The moment you stop worrying, the pain will go away. Run out and get tested for your peace of mind and put it behind you. You’re fine.