Okay Linda

Keep in mind I'm not a physician, I usually work with chronic injuries once they are diagnosed by a physician... soooo with that in mind, I am cautious with my advice. But here is some general info...

Piriformis syndrome often presents as more like sciatica type pain as it is generally nerve related as well. This means radiating pain in the buttocks, back of the thigh and sometimes the lower leg. Stretching the piriformis often aggravates it.

Ischiogluteal bursitis will usually present as pain very low in the buttocks close to or located on the ischial tuberosities (sitbones), often more achey... but only a physician that goes through a thorough assessment would be able to distinguish this for you. Sorry!!

One thing though, bursitis will not generally respond to massage and may become worse following treatment. So if that foam roller/ball is making things worse then maybe take a break, especially whilst in the acute stage! This may be your clue...

Not sure if this helps - best person to do a differential diagnosis is your PT or physician - but don't be afraid to ask about alternate diagnoses as they don't always look outside the box.

GG