K.H.
Not sure what it could be except that around 18m they do have seperation anxiety , even when they are being taken and left in a usual place , you would just need to persevere with that and reassure him that you will be back later for him , and also his age in general , they do become screamers/whiners and throw themselves around a lot around age 2 , so I think you will just have to ride it out. Sorry!