Okay, so first, your first STD testing was too soon. Your results came back on day 5, and gonorrhea and chlamydia shouldn't be tested for until at least day 5. Also, I don't know if you were already on the Amox when you tested, but if you were, that could give you false negatives.
Also, from what I can gather, you've been on Amox for 7 days, took 1G Azithromycin on day 12, Doxy for 21 days, which you are still on. This is a crap ton of antibiotics, and you haven't tested positive for any bacteria. Why are you taking these? What do they think you have?
You've also used gold bond, hydrocortisone 2.5%, coconut oil.
So, as you've likely suspected, you wouldn't see STD symptoms within hours. It would be a minimum of 2 days, likely longer. You had the swollen node before the encounter, if I'm understanding correctly.
Some of it, I suspect comes from the vigorous washing, which, by the way, does nothing to prevent infection. Once you're infected, you're infected. Some of it I wonder if you'd have gotten anyway, and the node was just a first symptom.
I don't know why you're on the doxy, and I wouldn't ever tell you to stop it if you're taking it under a doctor's orders. If you don't know why you're taking it, call your doctor and ask. 21 days is a long course of that.
I'd also suspect that some of this is a fungal infection in response to all the antibiotics. Perhaps it started as irritation or a reaction to the soap, and then developed into a fungal infection since you washed off the good bacteria that keeps everything in check - I don't know. Has anyone done any skin cultures or swabs? Has anyone cultured your urine to see if there's any bacteria or white blood cells?
If you don't know why you're on the doxy, find out and let me know that, too.