I've had multiple bladder infections and have taken antibiotics and been drinking cranberry juice. is there something else that could be causing it?

Several things: First you should urinate immediate before and after sex. Only wear cotton underwear. Avoid tampons for a few months.

Cause not addressed: Antibiotics alone isn't the panacea -no antibiotic will "get rid" of the infection meaningfully unless the underlying cause is addressed. Otherwise, it will recur. A urological evaluation is needed in women if repeated infections occur (in men , it need happen only once) to determine if there is an anatomical or physiological problem that can be fixed- only then can antibiotics finish the job.