Sounds like you have been over-enthusiastic with the Heal tool 
You might be able to go back in with the Clone tool (not Heal) and clone in the blue cloth from another location. Another possible tool is a heal selection plugin that you can add to Gimp.
Can you post just the part of the image with the stray hairs over the lapel ? (Select the area. Edit > Copy. Edit > Paste As > New Image. Export that and attach it)
You will get a better answer with something to work on.
You might be able to go back in with the Clone tool (not Heal) and clone in the blue cloth from another location. Another possible tool is a heal selection plugin that you can add to Gimp.
Can you post just the part of the image with the stray hairs over the lapel ? (Select the area. Edit > Copy. Edit > Paste As > New Image. Export that and attach it)
You will get a better answer with something to work on.