It's Encare Vaginal Inserts...I've used them in the past, but this time I don't know what happened, unless he's cheating.

They can irritate you or him, in which case you should discontinue using them. Try using another birth control, like condoms for a while and see if the burning goes away. If not, he should see his doctor, be examined and tested, if necessary.

I wouldn't assume or suspect anything, other than the inserts are causing the problem. Try something else and see what happens. I wish you both well.

The following was taken from this site about your insert:

"During use of spermicides, either partner may feel burning, stinging, warmth, itching, or other irritation of the skin, sex organs, anus, or rectum. Using a weaker strength of vaginal spermicide or one with different ingredients may be necessary. If you are using benzalkonium chloride suppositories, it may help to wet them before they are inserted into the vagina. If any of these effects continue after you have changed products, you may have an allergy to these products or an infection, and should contact a doctor as soon as possible."