have you heard of PURPLE crying? thoughts?

i recently took my almost 2mo old to the drs and his usual doc wasn't there so we saw a NP and i left feeling like she didn't hear me at all. baby's been spitting up more and it smells so sour, never likes to be on his back and has been clawing at me during morning feedings. he had a yeasty neck rash that we recently took care of but i have been assuming all his actions were in response to the pain of the rash but these are persisting. i pushed her to give me SOMETHING to try. my insurence has yet to give the go ahead for prevacid but my SIL (a pediatrics nurse with her masters), after encouraging me to TRY zantac, brought up PURPLE crying. after reading about it all night, i still can't decide where i stand on it. my first baby was so peaceful until about 1 1/2 years old where we got an early bout of 'terrible twos'. now i can't tell if i was just lucky with her and my boy is a screamer or he's actually in pain. looking for any thoughts -- i contacted his regular dr and am waiting for a response.