Hello, Thanks for the consult... Brief answer, Sore may be due to herpes genitalis Detailed answer, 1. You already metioned that you are hiv positive and 30weeks pregnant with CD4 count 600cells/mm3 2. The yellowish bump present on the pubis is due to herpes genitalis infection even thought you are not sexually active because the herpes will usually present in the body of hiv infected individual and start it s activity when the individual is immuno-supressed 3. Try to do the pus test taken from the yellowish bump on the pubic region for the herpes then you can see the result either positive or negative 4. For a negative result the cause of bump is due to bacterial infection Hope this information helps