Are all vaginal infections self-treatable?

No. Some yeast infections may respond to otc antifungals. If they dont respond then your doctor will prescribe a stronger antifungal either a cream or pill. Bacterial vaginosis and trichomonas needs to be treated with antibiotics.
The otc (over-the-counter) meds for vaginal infections are usually directed at susceptible yeast organisms only. They will not treat bacterial infections, or any kind of std - sexually-transmitted diseases. Get to a doctor, or clinic, and get checked.