He should see a doctor if it is not healing. It can be caused by many factors and just seem to have come at the time you think it did.
Yes, that is behaving in a selfish way. Any time you insist on sex with someone who is not wanting to have sex at that time, for any reason, it is selfish to keep pressing the issue.
Yedda Dancer said it straight. Think about how you would feel if you were having physical problems and he insisted that you have sex. (?)
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