SO you are using www.dyndns.org
to handle your Dynamic DNS needs, very nice, I use them too.. Who did you register your Domain name with ?
If you look around in the dyndns interface you will see you can register DNS names with them or transdfer existing DNS registrations to them.. if you transfer your existing dns name to them, you should be able to point it at your dynamic host and completely eliminate the use of yourhost.dyndns.org ..
Consult the support section of their site for more info:
I believe you will need to look at their Custom DNS service https://www.dyndns.com/services/dns/custom/
$25.00 a year isn't bad, give their sales or support team a call to verify this will satisfy your needs..