Constipated baby

My son started drinking formula at 2 months old. One month in started getting very constipated. Dr said try juice. We did and it helped for a while. Fast forward 5 months old. Juice didn’t help anymore. Back to the dr we went. She said try more fruits.... we did that. Don’t think it helped much. Family told us to try the kyro syrup and prunes and other things. Wic switched his formula 2 times. Nothing helped much so at 9 months we went back to the dr. She said well seams like it’s just Robert.... 🤬🤬🤦🏼‍♀️ my son would scream and cry and not breathe trying to poop. Took a whole day to get 2-3 hard ball turds out. After almost a week without pooping each time. His father and I decide to try him on almond milk at 9 1/2 months. (Everyone in our family is lactose intolerant) So we switched drs and after me telling her all that has gone on she agreed almond milk was a good idea. Because we’ve switched formulas and tried almost everything to help with no success. He’s been a BLW baby since 7 months old. So we watch what he eats. Now lately he’s been trying new foods and got constipated again like he was on the formula. I think it’s from him eating bananas 🤷🏼‍♀️ but I’m not sure. What should I stay away from so he doesn’t get constipated? Anyone else’s baby like this? Drs haven’t really helped much. We were supposed to see a GI dr for him but they never called us like they were supposed to. Just need some advise and maybe know that I’m not alone. I’m a first time mom and it sucks seeing my baby hurt and cry like that. Sorry this was long but I appreciate you if youve read this far!! And thanks in advance for any advise or tips.