I found myself having the same problem except my hair wasn't color treated. However I do a protein treatment 1 a week as well as a deep condition which has protein elements in it. along with the two I make sure to do some form of an oil treatment and together they have done wonders for my hair! I hope this helps.

3c, thin, low porosity.
Protein treatment: Vitale olive oil hair mayonnaise with oat protein, cholesterol, and botanicals
Deep conditioner: nuNATT treatment curly hair intensive mask with keratin and cupauaš˙ butter
Hot oil treatment: any