Head gasket or something else?

[Redland1]

My truck looses coolant from behind the water pump in real cold temps and when I park it I place a pan under it to catch the coolant.The last time I went to pre trip my truck the pan had about of gallon of coolant in it which was more than usual and also a leak on the ground in the backside of the motor which was new.I did some further investigating and shoved my phone on the back side of the motor and took some pics.Looks like coolant residue around the head gasket.I recently demandated it and removed the EGR but left the cooler in place but I have noticed coolant residue at the front of the cooler where the EGR used to feed in to and it comes back after cleaning it so don’t know if that’s the coolant traveling to the back of the block.Also the degas bottle looked like it had coolant on the low sight glass and I started the engine and proceeded to pour in the coolant in the pan but it pushed it out and continued to push it out until I put the cap on.Could it be that it got air in the system from losing coolant or is it something else? TIA