In the four scriptures we read (2 Cor. 12:7; Num 33:55; Joshua 23:13, Judges 2:3) we see that the use of the word ‘thorn in the flesh’, ‘thorn in your eyes’ and ‘thorn in your sides’ across the Bible is used by the writers as an expression in the same way today we would say someone was being a ‘pain in the side’ or other expressions like someone was going to ‘face the music’ or ‘get their act together.’ In interpreting these expressions you would take the meaning of whole phrase as one rather than focusing on each individual word.