Sometimes (maybe often) when babies are diagnosed with reflux, it's actually a food allergy or intolerance. Given that you have seen the symptoms worsen since starting solids, it would seem that there is a chance that this is what is going on with your DS. I think it would be worth consulting a dietician who specialises in food sensitivities (google the Dieticians Association and on their website you can find a dietician - select food sensitivities as a specialty). Also note that some dieticians do phone, email and Skype consultations so if you can't find one locally you can still get help. At least this will help to know whether this is the underlying issue or not.

In the meantime, I'd be tempted to reduce the solids and see if a smaller quantity eases things. Are you breastfeeding?