Losing coolent whilst driving.

[Dantreanor]

Hi all I have problem with my Ford connect 2014 1.6 the engine seems to be running on a lot of pressure. The coolent goes down to about an inch away from the main hose but water is sucked through the small hose near the top. I have had this changed as I thought this may of been cracked and lid replaced. As soon as the cap is removed the water refills to max. And when I checked the oil cap I noticed lots of air coming from the oil refil hole. When I open the coolent tank the pressure will release and top straight back to max. My oil is fine not smoking but if the dip stick isn't pressed it all the way it will make a lot of mess. I'm not losing any power still drives and sounds like new. My mechanic is suggesting the head is on it's way. It's been remapped to red and now has 50k. Any ideas? Thanks in advance
Dan