Deadlift

I don't know why but at lv 39 he evolved, problem solved

Hi, my Swinub is lv 38 and I refused his evolution between 33 and 35 in order to get earthquake faster than with a Piloswine, yet now that he has that move but since the lv 36 I don't have the possibility to made him evolve or not when he levels up any help possible ? Thanks