I'm honestly confused about normal hypermobility causing pain vs eds

My partner is more hypermobile than I am, and has a lot of gastrointestinal issues, is allergic to vibration and it's alleviated by taking antihistamines (riding bikes makes his hands itch, showers make him itch, back massager makes his entire back itch) and he gets sciatica flareups more than once a year with severe nerve pain

but idk if he's got eds, or if he's just hypermobile and his body bends itself into positions of pain and the other stuff is just irrelevant

and why do some people who are hypermobile never have health issues because of it lol muscle strength and luck?