When Sensitive is not Sensitive

When Joshua was colicky during the early weeks of his life, we switched to the most sensitive type of formula that Similac offers, Similac Alimentum.  At the time, there was a price war going on between a couple vendors, and we were able to get it for about the same price as Similar Sensitive (which is actually less sensitive than Alimentum).  He's not colicky anymore, but we've stayed on Alimentum because things have gone well, and it was just as cheap.

But recently the price of Alimentum went way up (back to the original expensive price), so we decided to see if we could step down to Sensitive. We switched a few days ago. The last two days Joshua has been extra fussy and generally very irritable and cries a lot. He often ends up looking like he does in this picture. We're not sure if it's related to not using Alimentum anymore or not. Perhaps it just coincided with him not feeling well. But if this keeps up for another day or two, we're going to bite the bullet and switch back to Alimentum, even at the higher cost.