taking a temp under the arm

[Vics128]

Hi, iv been trying to take my LOs temp as he felt hot earlier. Iv got a digital thermometer, relativly new, so batteries should be good.
Anyway the first reading came up as 36.1, but he felt pretty hot, so i tried it again, it went up to 36.5, so i tried again, and so on and so on untill it finally stopped going up at 37.7, does that mean thats what his temp is??
Also, should I add .5 degrees on as im taking it under the arm.
And lastly, if his temp is normally 36, when it goes up to 37, does this mean he does have a temp??