Scabies (Scabies) usually causes very intense itching (worse at night), small red bumps, and thin wavy “burrow” lines, commonly on finger webs, wrists, waist, and groin, while bed bug bites appear as itchy red welts in clusters or straight lines, often on exposed skin like arms, neck, and legs after sleeping. The key difference is that scabies spreads in skin folds with burrow tracks and persistent itching, whereas bed bug bites are more surface-level and appear in patterned clusters. You should see a dermatologist if the rash is spreading, very itchy, or unclear in cause for proper diagnosis and treatment.