Are there professional credentialing services to help me in the process? Are there any for non-US, international residents?

The Federation Credential Verification Service (FCVS) from the Federation of State Medical Boards is one, and The Universal Credentialing DataSource system developed by the Council for Affordable Quality Healthcare is another.

The AMA also has a fairly inexpensive service, but does not cover all specialties.  Foreign or international residents may find it well worth the investment to enlist a credentialing service because getting to sources of information may be more complicated.