I got a canker sore because I bit myself. Is it still bad to give oral sex since I got the canker sore when I accidentally bit my lip while eating?

Oral lesion. If you have an open wound, you are more at risk of contracting an STD. As for the sore, is this something you get frequently? If it's herpes labialis (blisters on the lip) you could give it to your partner. If it's a sore inside the mouth it is probably an aphthous ulcer or traumatic injury and is not contagious.