Is there any coolant in the oil? Remove the oil cap and look under it, is it white?
Any excessive presure building up in the coolant system from gases entering it?
Where is the coolant going? Is it overflowing from the expansion tank or anywhere else? If not, you may be burning it. How's the exhaust smell/look?

The water pump may be bad, if you see coolant leaking out the weep hole of the pump, then it's bad.

You could have a bad t-stat (even though it's new) or rad cap. It could just be air trapped in there, did you bleed the system?

You may have to have compression test and/or leak down test done to find out if the head gasket is bad.

How long does it take to start over heating? My aux fan rarely runs-especially this time of year.