the last number of posts remind me of exactly my situation.
i am about 17 mos post op with dr um for bilateral sh. still have pains in lower ab, si joint, tailbone, and adductor insertion.
i too did pilates after 6 mos out- not a good thing, i think it made me worse.
i too have nerve damage. i did not have an mri before my surgeries though, because my insurance (mvp in new york) would not approve of one, deeming it medically unnecessary! apparently i also had ripped my oblique(s) about an inch or two above the sh operation scar. that entrapped nerves. google "slapshot gut" or "hocky gut" and you might recognize something. i am not saying that others have had this as well but i don't know if um looks up that high when doing the sh surgery, and with no mri...
well, two reputable docs have told me i definitely tore those tissues and have massive scar tissue.
scar tissue can and will form in the injury and surgery! scar tissue causes pain for many, many people! it can grow over or very close to nerves which can cause nerve irritation. the ab muscles glide along each other in different directions, depending on the movement. the nerves pass through those layers. scar tissue impedes the movement and tugs on the nerves = ouch.
such pain will make your body lock up to protect that area, can affect the si joint, etc...
my sij has been in pain for a long time.
another thing to consider is the development of trigger points in the muscles attaching to the pelvis. those trigger pts can easily cuase the pains and dysfunctions that we are feeling.
in the past 4 mos i have been attacking those trigger pts after working with the scarring (still am working with scars) and it has allowed me to make leaps and bounds with some things.
perhaps a good phys med doc or even better an osteopath who does manipulations can help. definitely try neural therapy!