Am I Picking One Kid Over The Other

So my daughter is 12 and has HORRIBLE periods. She literally cried the whole time. Yesterday was the WORST. She sounded like me in labor. I called up a friend of mine who is a gynecologist. She said she could fit her in Tuesday. But if I couldn't make it she wouldn't be able to see her until next week. My son's urology appointment is Tuesday around the same time for his over active bladder. I went to ask him while he was doing homework if I could reschedule it and he said he didn't care. He doesn't really like going to them anyway because they embarrass him. I figured since his accidents haven't really gotten better or worse, more or less stayed the same, I could just reschedule and take him next week. My mother in law was supposed to drive us because my car is in the shop, but when I told her the change of plans she told me I'm playing favorites! I'm not. My daughter is just in so much pain and my son is fine with it. She says I also put my girls over my son which isn't true! I am closer with my girls because my son is 15. He's at that age where he doesn't really want to hang out with his mom. I asked my son if he felt that way and he said "No?" But my mother in law is making me feel like shit. Maybe it has to do with me and her son separating. IDK. Do you guys think I'm playing favorites.