I have a 4 week old baby bunny, help!!!?

Boy this vet is definitely not a bunny doc. They typically wean at about 8 weeks. Moms milk is not only needed for proper nutrition but for the babe to establish a healthy balance of good bacteria in his gut. Bunnies digestive systems are very delicate. Thing is that other animals milk is really not appropriate. Closest would be goats milk. At this point I would not give milk. Baby bunnies do grow very fast and have needs for protein and calories while they are growing. I would give a good quality pellet and a mix of alfalfa and timothy hay while he is growing. Because she was weaned so early I would wait a bit on greens veggies and fruit. Keep an eye out for loose stools. If this happens I would recommend a pro-biotic to help establish a good bacteria balance. I like probios. You can get it pretty cheaply at www.kvvet.com (by the way I get a lot of my prescription drugs there too. They are reliable and just a great company to do business with). Get the paste in the tube, just squirt out maybe a half inch and let him/her lick it off your fingers, most really like it. Give it once a day for a couple weeks then once a week for a couple more months. Once he/she(the reason I say this is even I cannot accurately sex at this age and I am good). is about full grown you will need to start limiting the pellet to about 1/4 cup per 5 pounds of body weight and switch over to timothy hay with maybe a small bit of alfalfa as a treat now and again. Wait till the babe is at least 13 weeks to introduce fresh foods though then start slow maybe a sprig of parsley and gradually add variety and quantity over a period of a couple months. Fruits and carrot should be fed sparingly because of the sugar content. Most fresh herbs are loved and are a good and healthy treat.