Hairless Red Bump underneath dog’s Nose

I noticed that my Dog has this bump underneath his nose 2 days ago, and it increased it’s size, he also licks his nose a lot. My dog is a Chihuahua mix, and 6 years old. Is this an infection and should I bring him to the vet?

Hello - I'm not convinced that this is caused by an infection.  Bacteria live on the skin all the time and the nose is generally protected with keratinised skin and mucous, so it is rare for eg bacteria alone to cause problems in that area.  However, there does appear to be a colour change to the nasal planum and a lump or  bump to the skin below it and I strongly reccommend letting your vet take a look at this sooner rather than later; samples or, indeed, further tests may be indicated.