What do I do ??

Okay so I have really strong vibes about my 15 year old sister being pregnant . She hasn't came out and told me anything but on Easter she had on white pants and she had spotting well her period is due and her boobs have been hurting she says and she informed me that she has had a lot of discharge but she has also had a yeast infection so that could be from that , but she hasn't started her period yet . I don't know what to do guys . My mom is a totally different person then she was while I was growing up she basically lets my sister do whatever she wants . And it really bothers me , because she hasn't offered to put my sister on BC like she nieve about it or something ? But my mom should know what goes through every 15 yr olds head . :/ I'm stressing about this so bad ..