your friend's symptoms are not related to his asthma, also if it was because of nerve injury
after stabbing and stitches ,it would have presented earlier and not after a year.
Most likely he has got fungal infection
or allergies. he should get his blood eosinophil count
done to check for allergies. skin cream containing Clotrimazole
will help incase of fungal infections.
Hope this helps.. stay healthy and stay cheerful.