Thanks for posting your query at DoctorSpring.com. I can understand your concern.
The anal area looks very infected. It might be a bacterial infection caused by staphylococcus aureus which would be common after an anal intercourse, there are some micro abrasions which allow the bacteria to enter and hence cause the infection. The second possibility is a contact dermatitis with the infection. The contact dermatitis might be due to the condom or the lubricant used.
I would recommend application of neosporin and cortisone cream twice a day for two weeks. In case there is no improvement within three days you will need to get a prescription for a higher strength steroid cream like mometasone and mupirocin cream. Also I would recommend a course of an oral antibiotic for ten days like doxycycline.
This will help in resolving the condition.
Hope this helps, please let me know if you have any queries.