<s>[INST] I was camping on the weekend and Saturday late morning noticed a purple round mark on my neck that looked like broken blood vessels. Later on in the day, the purple went away and it turned into a red swollen bump with a black spot in the middle. I tried to squeeze it and pus comes out of it. It is still very swollen and red 3 days later. [/INST] Hello! Thank you for the query. Pus presence clearly indicates an infection in this area. Such bump can be caused by a bug bite (as you have been camping recently). It can be also some bacterial infection due to a scratch for example. If it is not healing, and does not get better, I suggest you to consult dermatologist with this issue. Some antibiotics might be necessary to heal it. Hope this will help. Regards. </s>