RBE pretending not to be

I've been away for a few days and Nancy was showing the signs of being LBE until you look closely and and see her tight lips, sharp movements and distance viewing and in this state she is very unpredictable and possibly unsafe. What to do?  I put her on the 12' line and played the circling game - all fine, good responses and obedient but there was still something I wasn't happy with.  Yielded hind and fore - all ok.  Backup - hmm good average, but being RBE this is always a challenge so asked for sideways - ah ha, bingo here's the rub. She couldn't possibly go sideways.  She could yield her hind and fore if I was in zone 1, but move to zone 3 and her whole world collapsed.  Not only couldn't she do it but she was actually moving into the pressure and this was becoming dangerous.  We spent about 20 minutes with the phases going from -1 to +10 as she tried SO hard to follow my requests some seconds were very frantic and fast and one correct move gave us the much looked for Parelli Pause.  The only thing that kept me going was her attitude between the frantic resistances, she was very gentle and loving with her head in my arms.  Its very frightening pushing a horse like this for fear of losing the relationship.  We had another session today - and it needed only 3 minutes.  She did not want to go sideways, but obeyed my requests (phase 1) and moved slowly and hesitantly with a sharp leap at the end.   The 2nd one was good and we left that session and went to have some grass.  It appears to be her sholders that she finds so hard to move when she is under pressure.  I feel we have taken a big step forwards although there doesn't seem to be any obvious signs.