Talk to General Physician on Allergies,pimples On Chest

Assalam o Alaikum All respected Doctors,

I have attached a picture, please have a look..

My mother is suffering from this type of allergy, I don't know it's allergy or something else but she feels pain and irritation on this. it's on the chest area.

Also she is a diabetic patient, please guide what it is and what's the best solution.

Thanks