No relationship for what you are saying. The only explanation could be the bite was so severe cause terrible pain which can lead to weakness.
Otherwise, if this is not your husband's case, it could be because of stress
of not getting recovered from "biting the tongue".
Please be patient as everything would be ok. If the weakness persist, he can take some multivitamins to get enough energy. Feed him with healthy foods and get him plenty of fluids.