Maybe I missed one of your other posts, but why is your left side torn up? :shock: Have you seen a lactation consultant about the latch? I know things were pretty painful for us for the first week or so, but once the latch was adjusted it got better fast. If it's really too painful to feed on the left side, then yes, I'd try pumping it - you want to make sure your milk supply is well established on both sides and also want to avoid getting too engorged.
Usually you can start pumping to save after nursing is well established. Here, they recommend waiting until 6 weeks, but I'm not sure when you're going back to work... Also, you really only need 1 bottle's worth, if you can pump at work, because you'll just be pumping at the times when you'd normally feed so it'll even out!
As for the sneezing, babies just sneeze a lot! They're getting used to all the dust and stuff in the air. I don't remember it being more common after breastfeeding particularly, but it happened frequently!