I always have mouth ulcers after performing oral sex on my bf.usually lasts 10 days. what can be the cause of this?

Aphthous ulcers: Mouth ulcers are precipitated by a few different causes. They can arise from stress, trauma or of a viral nature. As long as they resolve in 7-10 days they should be considered benign. The fact that they appear consistently after the activity described should encourage you to look for an underlying cause and consult with your dentist or physician.

Trama: If the mouth ulcers occur inside the mouth, these are probably canker sores or aphthous ulcers. The trama from the activity to lips, cheeks and tongue can stimulate the sores to form. Body reaction to different triggers.