Certified GKH Gardening Expert
It sounds like you're doing everything right, but maybe you need to check your growing conditions against the info in these articles.
These plants prefer poor soil, so maybe your soil mixture is too rich. You may want to inspect your plant for pest infestation or mildew. Be very careful if you touch the plant, as the liquid it exudes can be toxic.
If the problem persists, you should contact your local agricultural extension office for additional info: https://www.gardeningknowhow.com/extension-search?zip=78382&radius=20&services_search_action=search&submit=Search