I've heard (from a number of reliable sources) that drinking a milk/formula bottle whilst lying flat on the back can be very aggravating on the ears. It can cause the milk to "pool" in the eustastian tubes - and milk grows bacteria pretty quickly so infection can set in. It does not happen with breastfeeding, apparantly, as the "suck" they use is much stronger and the milk does not do the same.
The recommendations I've heard for improved feeding is to give the bottle at least at a 45 degree angle - sitting upright is even better. My son has always fed his bottle this way and has never (touch wood!) had an ear infection to date.
I can confirm that using echinacia tincture is great to help fight the bug if you have it (its a general immune system booster) - but cannot be taken for longer than 3 weeks at a time. Use 5 drops in water, 3 times a day.