Hi @tbrooks57. From what other members have shared in the forum, sometimes trying to find the root cause of ITP can be frustrating. Underlying infections or certain viral infections such as Epstein-Barr virus (EBV) and cytomegalovirus (CMV), have been linked to the onset of ITP.
According the Mayo website, “In adults, an infection with HIV, hepatitis or the bacteria that causes stomach ulcers, known as H. pylori, can cause ITP.” Also having underlying conditions in which there is an inflammatory response such as rheumatoid arthritis, lupus or other inflammatory can be another trigger. So you can understand how trying to find the culprit can be like unraveling a mystery.
https://www.mayoclinic.org/diseases-conditions/idiopathic-thrombocytopenic-purpura/symptoms-causes/syc-20352325
Our immune systems are incredibly complex, always on patrol to keep us healthy from any potential invading threat/attackers such as bacteria, fungi or viruses. Occasionally, there’s a miscue and the immune system may end up attacking healthy cells. With ITP the immune system attacks and destroys platelets.

Since you’re new to the forum and you mentioned having other health conditions, I’d love to provide links to relevant discussions for you. Mayo Connect has over 70+ support groups. Would you mind sharing your other conditions?