Hi..
Can understand your concern..
As per your complain bump in mouth just 2 to 4 days after
oral sex cannot be simply diagnosed for HIV as the HIV virus does not immediately becomes activated in the body and cause a bump..
Another viral infection known as
Herpes causes cold sores and can be sexually transmitted can cause bump but it also takes a comparatively longer time to give symptoms if you were not previously exposed while there can be a chance that there can be an outbreak in case if there is history of previous infection..
The bump can also be simply an apthous ulcer or a
canker sore or a traumatic ulcer caused due to rubbing of the private part of your partner over the mucosa of your mouth..
You should do salt water rinses..
In case if there is any pain you can take anti inflammatory painkiller like
Ibuprofen..
Hydrogen peroxide gargles can also help..
Maintain a good
oral hygiene..
In case if the bump does not reduce in size or there are more outbreaks you should
consult a dentist and get evaluated..
Hope this information helps..
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Thanks and regards..
Dr.Honey Nandwani Arora.