Edit: about block-feeding... I started doing this too when I was self-diagnosing the problem. The lactation specialist I met with said this can actually screw up your milk supply so unless you are sure that your problem is with hindmilk/foremilk imbalance, I would not do this. I really do encourage you to work with both a lactation specialist and an allergist instead of tryin to work this out yourself. I was so grateful for the help they provided me....Good luck :-)
Don't give up and don't beat yourself up! All 3 of mine had milk protein intolerance. They were rashy fussy babies and had green stool with blood at times :-(
a few suggestions.....
Stop both dairy and soy. The proteins are similar and it is common for babies to be bothered by both.
Seek help from a lactation specialist .... Either through your hospital or privately. I did this with my third as I was worried about a fast let down and foremilk/hindmilk imbalance. Meeting with the lactation specialist was invaluable.... She helped me determine that the actual nursing wasn't the issue.... So in essence helped narrow down the cause of my baby's issues.
It can take several weeks for allif the dairy/soy to leave your baby's system so symptoms can take quite a while to clear up. If, however, you feel like eliminating the dairy and soy isn't fixing all the problems, I would REALLY encourage you to have your child allergy tested. My middle child only slightly improved after stopping the dairy and soy. My pediatrician had us go see an allergist. She tested positive for true food allergies -dairy, egg and nuts! We were sent home with an EpiPen and a newlist of foods to avoid. After stopping the dairy, soy,eggs and nuts she was like a new baby. So.... Long story short, your baby can have MSPI (milk soy protein intolerance) and/or other significant true food allergies causing problems.
Don't let anyone tell you that you can't test a baby for food allergies either. Not true. A simple skin test can really help provide valuable information.
I hope I didn't ramble too much. In short, Be patient, cut out soy too, get some help from a lactation specialist and an allergist.
Best of luck. Keep nursing as long as you can.... Really is doing baby more good than harm.... I hope you get some answers.