8 month old having night wakings from constipation

Has this happened to anyone else? At 6.5 months my sleep trained baby started waking at random times in the night crying. That us very unlike him and even in a sleep regression I usually see a couple nights of waking at the same time of night /early morning fussing, but never screaming at random times a night. We tried EVERYTHING and even spoke with a sleep consultant and she said we're doing everything right. I finally thought back to when the wakings first started and it was right when he started having 3 solids meals a day. We stopped giving him all the constipating foods and started giving him all the foods that are supposed to help popping and he has finally slept through the night the last 10 days after 2 months of wakings. It doesn't always help though because he hasn't pooped the last two days and has been uncomfortable and woke up last night crying at 3am. Has anyone else's babies had wakings from tummy troubles/solids? Anyone have any other tricks for getting baby to poop besides what we're already doing (fiber rich fruits and vegetables, mommy's bliss constipation ease, plenty of water, warm bath, tummy massage, more breast milk, daily probiotic, bicycle legs, tummy time, even tried the rectal thermometer just once)?