sick budgie

ive bought a budgie today,settled him into his new home,ive noticed his bottom area is really sticky and dirty and smells. what can i do ,to make him better.

[Aleda M Cheng, D.V.M., C.V.A]

Birds can be afflicted with diarrhea and gastrointestinal parasites just as other non-bird species can.  

Since you have just purchased your bird he was sick when you purchased him.  Please bring him back to the store.  The employees at the store should be able to help with medicine for him.  Most pet stores also have veterinarians in their employ who can be contacted for treatment.  If the store does not offer this service than you will either have to contact a vet on your own who is knowledgeable about bird medicine or you must contact the store for a refund or an exchange for a healthy bird.