What Could Be Causing My Puffy Nipples That Shrink When Touched?

Hy doctor, I’m 21 yrs old male and my nipples are very strange. They are usually puffy but when I touch them they become small and normal, again changes into puffy form when gets warm nearby. Can you please resolve this problem of mine as i am very shy person and cannot take off my shirt and walk openly at beaches. Or at home