It seems that your grand son may be having pompholyx
It is a type of eczema characterised by vesicular eruptions on the sole and palm.
There may be itching and pain.
As it is on soles,it is called pedopompholyx.
Exact cause is not known.
There may be triggering factors like chemicals like perfume,local drug like neomycin
,stress, fungal infection
,metals like nickle or cobalt..etc
It may be aggravated by solvent,water and detergent.
Soak or compresses by vinegar in water solution may improve the condition. It may be done 4 times a day.
Local application of steroid
or antifungal cream may be done.
Oral antihistaminics and steroid in tappering dose may be given.
I think your grand son may be alright, still you consult dermatologist
I hope you got my answer.
Dr. Ilyas Patel MD