How do I comfort a teenage girl cramping immensely and aggravated?

She was diagnosed with dysmenorrhea 2 years ago. Normal over the counter painkillers are useless so I normally get monthly prescription drugs from the gyno. They help but usually takes a long time to provide relief. She has to miss school the first 3 days every month as she's unable to focus.

They have tested her for endometriosis and fibroids, all to no avail.

Sometimes, I feel so HELPLESS seeing my baby that way.