I have the exact same problem, and my surgeon recommend I take Vita4Life multi’s without Iron. I’ve been taking them daily for months and I’ve been great so far. I still take iron supplements, but I take them separately from my multi and every other day. It has helped immensely with my Constipation issues. You may want to check them out. Here’s the link. J
http://vita4life.net/products/bariatric-vitamins-comprehensive-mini-multi-vitamin-no-iron-formula.html