Strange blue veins/spot on chicken comb

[Mahoo]

Hi. My hen has these strange blue veins on her comb. I have checked her vent. Can not see any mites. She is eating and drinking as normal and running for treats and in no way seems unwell. She has for a few weeks had a wheeze which I’ve been using a tonic for chickens which helps with breathing issues. This hasn’t improved. Any ideas ?

 

[Mahoo]

Not sure if the photo I posted worked so thought I would try again