Not every sexual encounter with someone who has an STD will result in transmission.
Many STD's do not have symptoms. HIV is a perfect example of this. Except for a short term bout of "flu like" symptoms two to six weeks after transmission, this disease has NO symptoms for many years. Thus, there are many walking around infected totally unaware that they have this virus.
Unless HE gets tested he'll never know if he is STD free.
If this helps...an HIV screening test done one month after a potential exposure is considered to be 95 percent accurate; that is, approximately 95 percent of newly infected folks will have enough antibodies present (this is what the ELISA screening test checks for) to be picked up by this test.
Many who cannot wait the three months get tested at one month, then retested at three.
You text her and say you are having symptoms that worry you regarding HIV and wonder if she has had a screening test lately and if not, would she agree to one.
If you have a "bump" caused by an STD you already have the STD and the bump is simply a symptom of the STD. Brushing it with a toothbrush and then brushing your gums would not suddenly transmit a new STD to your gums.
In addition, if you've had this bump for "many years" it's highly unlikely it's a symptoms of an STD.