weird blister?

i have this weird thing. it kinda looks like a stretch mark but on one end it has what i *think* is a blister, it's just like a lot of fluid under a think price of skin, and on the other end it's like a white head i keep popping and it won't go away. ik i probably need to go to the dr but my mother is really weird and she's just gonna be dramatic or day it's nothing, she's always one extreme or the other & im a minor so i can't go to the dr by myself. i just want a idea of what it is, ive had it for months