My Shih Tzu has white bumps in her chin area

Hi pet owners, my 10 year old shih tzu has been really itchy lately. I went through her fur with a pointy comb specifically looking where i see her scratching but don't see anything odd or irritated. I did see some dark freckles or moles on her body however, not sure if i should be alarmed. I included photos just in case.

My real concern are the white bumps around her chin. I remember taking her to vet on this about 5 years ago and they gave me something topical but i cant remember what it was or if it improved. At that time the vet didn't think it was something i should be overly concerned about so i didn't either. I hate to see her uncomfortable itching and wondered if anyone else has noticed this on their dog and what they did.