Always Constipated...Help!?

Br

My girl has never been a big pooper but its been worse the last two months since she started solids. She is 8 months old on Tuesday and I dont know what I can do. I have tried everything.

-She eats prunes almost everyday.

-We try to give her more fluids when she will take them.

-We feed her the 'pooping foods' everyday.

-She gets watered down applejuice when it gets really bad. (2x a week)

- We avoid grains most of the time because it makes it worst.

- She gets lots of baby massages too.

I dont know what else to try. She is growing slower and the doctor thinks grains solve everything but that is literally the one food that has her crying while trying to go.

Any ideas? Any at all?