I saw my doctor today and during the visit, he asked me to lift my arms and he reached his hands up into each of my armpits. it was rather ticklish. can someone tell me why he did that, just out of curiosity?

Trying to feel enlarged lymph nodes in the axillary areas, an important part of the physical exam, with similar areas being the sides of neck, under the jaw and in the groins.

He was checking for enlarged lymph glands or other masses within the axillae (armpits) but when we teach medical students the proper way to examine the axillae, we have the patients hold their arms down against the rib cage, as lifting the arms upwards causes the contents of the axillae to retract upwards and too far inwards to palpate the axillae contents properly.