Hi no std symptoms appear the next day so its most likely an injury from the act itself.
I can't answer your question, but just posted one of my own on a related topic.
Two months ago I gave oral sex to a woman (no intercourse and I did not receive oral from her). The next day my lingual frenulum hurt and had swollen bumps on both sides. Then I got swollen areas on the floor of the mouth. Then my geographic tongue (a life-long condition) got worse with lesions on the sides of it. At the same time, tiny white bumps appeared externally on my upper lip. I've been to many doctors, including a dermatologist. I've been tested for every STD (some several times) through blood tests and brush scopes. Everything is negative. Two month later no one knows what is going on. The woman I was with got tested and she had no infections.
I was convinced I didn't have an STD. but....
Yesterday when taking a shower I saw a red spot on the shaft of my penis. It looked almost like a little crack in the skin with red around it. I thought maybe it was just that and tried not to worry. Today the crack is still there but the red is gone. However, there is a second spot. Only this one is just behind the head and is a small red raised bump.
Sure, they could be nothing. But I've never had "nothing" like this before.
I'm even more worried now than ever before.