A generation or two ago, when you had a medical question, the solution was obvious: Ask your doctor. But these days, as trust in doctors and other traditional medical authorities like the Centers for Disease Control and Prevention has eroded, Americans are more and more likely to consult their Instagram or TikTok feed. According to a major new study of popular health- and wellness-related influencers from the Pew Research Center, 40 percent of Americans — and half of adults under the age of 50 — get medical and/or wellness information from social media accounts. What they’re encountering is a chaotic ecosystem where MDs promoting evidence-based medicine coexist alongside life coaches selling unproven peptides . Nuanced portrayals of mental health problems and how to manage them commingle with accounts that blend Jungian psychology and astrology .…