Prolotherapy in addition to pt for spinal neck disc bulge? Does it make sense, tighten ligament to reduce bulge?

Not to me. I think of disc bulges as asymptomatic incidental findings until steroid injection improve target neurological symptoms symptoms.
Controversial. Prolotherapy is a somewhat controversial treatment and is not commonly used. A 2010 cochrane review found that in 3 studies, prolotherapy alone was not effective for treatment of chronic low back pain, and in 2 other studies prolotherapy in combination with other treatments was effective (thus not clear whether prolotherapy was the effective part of the combination treatment).