Skin changes

Good day, My 2-year-old dachshund has something like a yellow blister on her chest and swollen red under her armpit. I also notice red dots on her belly.  It started yesterday after her walk.. If somebody knows what could it be? Thank you

Redness of the skin like that is pretty common - and is typically due to inflammation. Common causes include parasites like fleas or mites, skin infections, and allergies, like contact dermatitis. The yellow blister-like lesion is a bit more worrying - we typically see these with more severe skin infections, or with some auto-immune diseases. I’d say he could do with a vet check to be honest - some of the possible causes are quite serious and need aggressive treatment.