I have excessive clear vaginal discharge accompanied by pain and air bubbles, what could this be ?

Infection: Most likely trichomonas vaginalis infection, you will need to get pelvic exam and treatment. On occassion, it could just be a different infection - gardenerella vaginalis- also treatable, or some women just have natural discharge - which needs no treatment- the bubbless lead me to think of trich. Also if this is the case, your partner should be treated too-and use condoms!