@donna61--When I was looking for a chiropractor to work with my children I contacted several sources. There are several national and international associations that certify chiropractors to work with infants. You can search online to find a list of them.
A lot of chiropractors work with infants without the certification, but I like the idea of them having some additional training in this area. I don't think it's mandatory, just a good idea in my opinion. It really helped to put my mind at ease.