Is it normal to get tearing at the vaginal opening after using cream to treat a yeast infection? the infection spread to anus. same problem with tears

Yes: Yes, this is so painful, right? It's more that the skin is splitting, i'm guessing. Sometimes you can use some desitin (zinc oxide diaper cream) or similar cream (for diaper rashes). This can help that skin to heal. This tearing could be due to the infection from yeast, or it could be your skins' reaction to some ingredients in the ant-fungal cream.