I agree w/ Girlie.
Hip joint pain was one of my primary Lyme sx and I had all sorts of problems sitting, walking, lying down. Sometimes the hip would lock up, and when I could walk I would walk with my hips at an angle because it hurt less. Weird, wild stuff.
I think he'll probably do well if he continues the abx regimen for awhile longer. My Lyme-knowledgeable neuro suggested that most neuro sx are from inflammation so he might also try anti-inflammatories like japanese knotweed and turmeric. And as Girlie mentioned - detoxing is key. Also, be sure to protect his gut health.
Chronic late-stage lyme—likely infected in '00; Clinically dx Mar'14 w/ Babs, Fry Labs+ Bart-like, CDC+ Bb. First treated 4-5 viruses & GI/immune. Herbal antimicrobials in May; IV port-started Rocephin in Nov; added vancomycin Mar'16;
DETOX: Pinella/Burbur/Parsley/Milk thistle/Burdock/Red root; Samento/Banderol/Enula; JK/Turmeric; BFM-1; antifung; many many supps; cholestyramine!