My daughter has been suffering with her bowels pretty much since birth. She was breast fed until 8 weeks then switched onto aptamil 1. when she was about 12 weeks old, her stools turned acidic, green, foul smelling and loose. they are still like this now and she is 10 months old. she was 9lb 20z born and is now about 20lb 10oz. her weight did drop off when the problem started but she is now up to her centile line again. she is now on apatmil 3 3 x 7oz with 3 meals as well. these stools burn her skin and stain her clothes and cause her pain. queried lactose intolerance but nutramigen didnt work so been ruled out.
As her weight gain is appropriate I do not think there is anything for you to worry about. The color of the stools being green and mildly acidic is very much normal in this age group as long as the baby's weight gain and development are appropriate.
Hope I have answered your query. Let me know if I can assist you further.