Hi Kristjanmn,
It looks as though you have reached the texture limit for your material at present. The maximum amount of texture samples a material can use by default is 16, 4 of which as used for rendering, so 12. However, this limitation can be removed by going to each texture sample node in your material and setting the sample source to shared:wrap. Try doing this to see if it fixes your material. If not, try painting over the affected component with a single material at full strength, then see if you can paint over that area again.