issues with domain.com/admin

So, I just migrated my site and ever since I cant login using domain.com/admin

I can only login define the wp-admin path by going to domain.com/wp-admin

I noticed when migrating I had some real issues changing the SITE URL or SITE PATH after migrating from the old hosting/domain. I was told there was code in the wp-config.php something like define_sitepath or something, but nothing like this so I ended up changing the settings in the database.

Any ideas?

This is also effecting the contact form, the form cannot submit due to a 404 error which I would imagine is related.

Thanks