Hi My Baby Has Watery Stool For 4 Month ,

hi
my baby has watery stool for 4 month , his weight increase 400 gr per month
he has 9 month years old
his stool test: reducing substance 3+
wbc 0-8
and one time I see blood his stool
he drink breast milk and I dont eat dairy and many other thing
what is your suggest for me? I must continue my diet? I am tired from diet and he has watery stool yet
only some days he had blood in stool
thank you very much