My daughter did the SAME THING AT THIS AGE. I was breast feeding her, altered my diet and she still strained. My Dr had us see a specialist...while my mother (of 10) said to change to Allimentum or Neutramogen. The Dr did a scope and saw nothing wrong. I changed her formula over and within a day or so she stopped straining. (It takes 1 to 3 days to see the change.) All of my kids have had allergies/sensitivities to milk base formula/dairy. (Even soy)Save her the agony and change to one of the above formulas. Don't just treat her for constipation..you need to understand WHY she is straining and/or is constipated. If you don't, she will continue to have this problem. Like I said, save her the agony and treat the core issue. Her diet. You may need to wait a bit longer before you introduce new items to her diet and be sure to try 1 thing at a time. Keep the fancy baby foods from her until she adjusts to each one. None of the mixes...I promise you that I know what I am talking about. Their digestive systems need time to develop too....so you may find that you need to wait beyond a year to introduce milk to her. Let me know how she does, if you follow my advice. Please let me know. I hated seeing my daughter go through this too. I know how you feel. Believe me. My last child had it so much easier because I had it all figured out.