Skin cancer?

Ive been seeing this big mole on my bfs leg but kinda shrugged it off when i encountered a post about cancer i immediately asked him if hes alright and what that mole was. He just said its bumpy and been there since he was hs. Hes 22 now and weve been apart for 3 months hes in us. Ive been nagging him to tell her mom because shes a nurse and she might know what it is. She just told him that its nothing. She didnt even get to look closely or touch it. Right now both of her parents are working and get home evey night. He cant go to hospital because he has a 9 year old brother to look for when theyre not around. The mole is about the size of a pinky nail and bumpy. Can anyone tell me what this is or give me advice what to do?