Throwing up?

DS had a stomach bug a couple weeks ago.  We did the whole electrolyte diet for a few days until he could start eating again.  Fast forward to yesterday, and both DH and I came down with a NASTY stomach bug.  Well, last night DS threw up his afternoon bottle.  This morning he threw up his morning bottle.  He's not drinking as much out of his bottles as he used to (he would polish off 6-8 oz no problem and now he's getting maybe 4-5 at a sitting).  I'm wondering if this is related to the stomach bug and he has a touch of it again (which doesn't make total sense because he IS still eating and keeping most of his food down) or if it has to do with teething (he seems to be super uncomfortable lately and always gnawing on something) or his gag reflex is just kicked up a notch.  Last night DH was giving him peas, and he kind of gagged on one and that's when his bottle came up.  This morning he was eating Puffs and he again sort of gagged and then threw up his bottle.

I'm hoping and praying this isn't the start of the stomach bug in him...but does anyone else have experience with something like this?  Could it be related to teething?  Gag reflex?  (He was eating finger foods just fine a week ago so I don't know why all of the sudden it'd bother him...)  Thanks!