OTHER THINGS YOU CAN TRY
Bicarbonate of soda
Mix baking soda with a small amount of water to make a 'slurry'. Apply this to the stained garment with a toothbrush and follow the same method as above. Try the mixture on a small area of your garment first, to test its colour-fastness.
Vinegar soak
Soak the stained part of the garment in a container of white vinegar. After an hour, brush it with a toothbrush. Again, try on a small patch of fabric first to test for colour fastness. Afterwards, wash the garment in a washing machine, to get rid of any vinegar smell.