i also have skin asthma since i was born, because its hereditary,my skin asthma are like black spots, everytime i get bitten by mosquito then i scratch it it turns black,i have them in my legs and arms only, because its more exposed,its really hard to have skin asthma.because of this i have lost my confidence in meeting new people. i went to derma several times. and they all tell me the same just like what apple_dy says. use hypo allergenic diet. foods that are not to be taken:

>chicken

>egg

>eggplant

>seafoods

>soy sauce, fish oil and other condiments

>citrus fruits(orange,mango,pineapple)

>use lotion: cetaphil, aveeno. use 2-3 times a day.

>avoid soaking in the water for too long. so dont take a bath too long!

>use lotion after every bath.

>when in swimming pool.use lotion afterwards.

always use hypo allergenic things (make up etc.

>perfumes are not allowed for the skin!

thats all you need to do. its really hard.ive only done it for 3 months so my skin asthma is still here. hope it helps you.please reply any comment.tnx!