tiger bomb from compound genetics

If it's just the stem, it's usually sunburn and will not spread to other parts of the plant. If it's in your flowers, it's most likely in need of more phosphorus. Don't go too crazy or you'll lockout calmag. Luck mate!

You should only add cal/mg in soil about every 2 weeks if you see they need a little. Its probably building up in your soil if you add cal/mg every time. Cheers friend