The number of med-spas, weight-loss clinics, and concierge practices where patients pay a membership fee for direct, often same-day access to physicians, has exploded in recent years. But while patients pay for these services out-of-pocket, providers still often rely on software built for traditional, insurance-based care. VITL , an 18-month-old startup, claims to be solving one of the sector’s biggest tech bottlenecks by building an e-prescribing platform — a digital tool for sending and managing prescriptions — tailored for cash-pay medical businesses. On Wednesday, VITL announced a $7.5 million Series A funding round led by SignalFire. Founder and CEO Charlie Jordan built the Nashville-based company after realizing just how much time medical providers spend managing prescriptions for treatments not covered by insurance.…