B.B.
It's not uncommon for a baby to refuse a bottle after being breastfed exclusively for the first months. Here are some tips to help your baby make the transition:
Don't be the one to try it first. The shift may prove easier if someone else, such as your partner, introduces the bottle. Your baby can smell your milk from at least 20 feet away, so it may be best to remove the temptation, even by having you leave the house.
Entice your baby with the bottle nipple. Try warming the nipple a bit with warm water and even putting a little breast milk on it. Allow your baby to play with or chew on the nipple to get used to it. It may also help to choose a nipple that's similar to your baby's pacifier, if he has one.
Offer lots of love. Provide as much affection and physical attention when you give the bottle as you would when breastfeeding.
Try different times or positions. Bottle feeding may go more easily if you feed slightly later than you normally would, when your baby is really hungry. Holding your baby more upright than when he's nursing may also help break the expectation of breast milk.
Offer a cup. If your baby continues to reject a bottle, try a cup instead. This is a messy and not always productive task with a 4-month-old, so it's best for just occasional feedings. Hold your baby upright and tilt the cup slowly and carefully. Some moms continue breastfeeding (without expressing or supplementing with formula) until their babies can manage a cup well, around 6 to 8 months.
I just read this moments before I read what you wrote-- It was sent to me for my 4 month old son but what's a couple weeks LOL I hope it helps at all :)
B.