Breastfed baby is constipated

Hey ladies,

So let me start by saying I knew when I started solids we may have to face constipation, but my little one has been dealing with this for 2 days now. Any recommendations? I usually feed him a fruit and veggies mix with oatmeal (multigrain) in the morning, fruit for lunch and veggies for dinner. The past few days we did have a banana and apple with breakfast and lunch....he's had prunes and all of his poops are like pellets. He's eaten a lot of different foods since he was 6 month, and never had an issue. We used to still get "looser" stools up until just two days ago. Anyone have recommendations?