While I was having sex
My condom broke open
I did not notice any symptoms
But after 12 days
I started feeling butt pain
Below abdomen and above rectal
This middle area is pain
This pain comes and goes
Could it be an std
I got tested for hiv it came back negative
I completely understand your curiosity about this. When a part of our body is acting unusual, especially the butt, we look for quick answers from people on the Internet. Unfortunately, the only person who can even begin to speculate on the state of your anus is a person who has seen you, looked down on your butt, and took tests or samples in order to find out what's going on down there.
The circumstances of your question are a little bit confusing to me. You state that while you were having that YOUR condom broke, "My condom..." So, if you were the partner wearing the condom, how would an STI symptom ended up in your butt? In order to have an STI located in the butt, one would have needed to have been exposed in that area. If one is ONLY the top (or insertive) partner, the butt wouldn't be showing symptoms of a possible STI.
Unfortunately, many providers don't test the butt nearly enough. That is because they don't know how important it is for men's sexual health (guidelines about butt swabbing only just started being used around 2011). Many don't know that a gonorrhea or chlamydia infection can live inside the butt for years causing minimal pain, more like irritation and itching.
There are so many reasons we may have pain in our butts. If you're the bottom during anal sex, you may have residual pain from tearing or pain from aggressive fucking. But we can also have pain for non-sexual reasons like hemorrhoids, anal fissures, splits after shitting, and so on.
You already know you are HIV negative. I would encourage you to speak with a qualified health care professional about the other concerns causing you discomfort or uncertainly in your butt. It is the only real way you will get answers and clarity about what to do next.