Reflux sometimes does get worse on solids, though some GPs will tell you 'it should get better' - I've seen countless MNers say their LO's reflux has got worse for a while. My dd2's did, too.
I would definitely talk to the GP about reflux. Some are well informed, some are not (mine wasn't, initially) so if you feel fobbed off I would push for a referral to a paediatrician.
The medicine that helped my dd was Ranitidine, and Domperidone, both given three times daily (I put it in her milk, eventually, much easier!) but some LOs take stronger meds such as Omeprazole, I think. The first line med for most GPs is Infant Gaviscon, which I think is probably less useful when a baby is weaned and which didnt' work at all with dd - just made her constipated, which made matters worse.
TBH, I found cranial osteopathy very helpful with dd1's cricked neck (transverse lie through most of my pg) but didn't do a thing for dd2's reflux, which needed medicating...though maybe others have had different experiences.
Whatever your ds's problem, I think you are absolutely right to seek help with the vomiting - it shouldn't be that frequent, and must make his life harder as well as yours: you both deserve some answers! Good luck, let us know what the GP says...