Not sure about the spit up...my DS was "silent" reflux (he would bring it up but swallow it back down, rarely actually spitting up). To me the tell tale signs though is the grunting and squirming. My DS did lots of grunting. he started immediately after being born, they originally thought it was grunting to breath but quickly, even in the hospital, we found it was reflux.
When we brought him home family & friends would say he sounded like a billy goat! and the crying....wow...people would tell me it was colic. After some research I found colic usually occurs for a specific amount of time at near the same time each day. he would scream ALL the time. he would gag and choke sometimes when nursing that it would scare me to death. And even though he seemed uncomfortable and upset he wanted to nurse constantly!
What we found is that he was comfort nursing becuase as the acid came up it would burn, the milk has a cooling sensation. But it is a double edged sword, the fuller their tummies the more it comes up! Also, the gaggin etc was because as he was drinking it was also trying to come up at the same time so it would cause him to gag and asperate into his lungs.
I don't want to scare you....my DS had a pretty severe case of GERD (reflux disease) and Esophageal Dysphagia. Lots of kiddos with reflux out grow it pretty quickly, by a few months even. at times I thought it would never get better but at 30 months my DS is off all medicines and only shows signs every once in awhile, so if it is reflux it will get better. If you talk to your doctor about it ask about doing a trial of Prevacid 15 mg solutabs. They disolve on babys tongue (you hold it in his mouth) or even in a little water and give through a medicine syringe. it is the only thing that helped my DS and lots of other kiddos I know.
A good resource for you also may be www.kidshealthsupport.proboards.com It used to be called Moms Wearing Puke....support for reflux mamas. Got me through many a rough days & nights! Also, feel free to message me if you have any other questions.
Good luck and take care!