How common is it for a thin 15 year old female to have bulging discs at l4-5 and l5-s1? she has pain when getting up from a sitting position

Best have her seen : By her doctor, who may refer to specialists to rule out a connective tissue disorder ( like marfan's syndrome or ehlers-danlos). It sounds like she needs to see a pediatric neurologist for headaches & blurred vision & have an MRI of her brain & spine, if she hasn't already. A pediatric ophthalmologist & a geneticist may also help. Call her doctor for recommendations for after-hours care.

Disc bulges: Disc bulges are best considered as asymptomatic incidental findings not used as an explanation for a pain complaint just keep looking for pain generator rule out muscluar pain first, the evidence for disc bulges are painful is weak, and subjective , biased and leads to no effective treatments that uphold the first do no harm ethos one guys opinionl after14 years of experience it.