It's nice to meet you. PPMS is an unusual form of MS only affecting about 10% of MS patients. It typically does not follow the noticable attacks of other types, but instead slowly (usually so slow you dont notice) getting worse over time. My husband also has this type and went for more than a decade before he was diagnosed.
Not so much info out there on it unfortunately, probably due to the few that have it and limited amount of research that's been done on this particular form. I'd be more than happy to share what info I have though, been researching a long time =)