Sores in the genital area and mouth can indicate herpes infection.
This can be transmitted by kissing and mouth to mouth contact also.
Oral intercourse also can lead to transmission of herpes.
Of course, it could be other conditions leading to sores and blisters ( other infections which are not that common ), but herpes is the first condition which should be ruled out.
Please visit a gynecologist and have her tested for Herpes and other sexually transmitted diseases.
Kissing and mouth to mouth contact suffices to acquire herpes.
All the best.
Please feel free to ask for further clarifications.