A Baclofen pump seems to me something to try after everything else has been explored. It might be that no one singular med will help, but a combination. Spasticity can pull hips and spine out of whack, particularly if muscles are weak, and cause extra pain.
I relay the below not to talk about myself, but just to show what kind of options there may be.
I take a combo of Tizanidine and Gabapentin for spasticity. Fatigued muscles and joint pain seemed to be more affected by spasticity, so it was a loop that I needed to break- as spasticity caused muscle fatigue and pain, which triggered yet more spasticity. For arthritis and muscular pain, with sometimes awkward posture and joint immobility caused by spasticity, Celebrex. I have also been fortunate enough to receive some help from a pain doc who has done some nerve blocking/ablation in my lower spine to help with leg and hip pain.
I don't know what your PALS has tried, but it can sometimes take some time and effort on the part of the physician to find a combination of meds to help out. It might also be helpful to get a referral to a physiatrist or pain specialist, who would have many tools to help.