It could be an age thing. Honestly, I'd stop the solids altogether for at least a week or so, see how you go, then gradually reintroduce (if you want to) and again, see how you go.
DS had silent reflux early on, not to the extent that he needed medication or anythign mind you, but we had similar issues when he first started eating at 6 months and found stoping for a bit helped. If his digestive system is struggling it makes sense to keep it 'easy' for him, I think.
Anyway, hope things settle down for the little guy soon