I have these little brown bumps on the stems of my hibiscus tree.
Little Brown Bumps on the Stems of My Hibiscus
Certified GKH Gardening Expert
It sounds like either scale or mealybugs are affecting your plant. This can be treated with neem oil. Here are some articles that should help: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm