The Doctor wakes up to find nothing but empty sheets by his side, leaving him to wonder where River had gone. He jumps from bed and steps into some pajama pants and slippers to walk to the console room of the TARDIS where he spots River pulling levers and pushing buttons.
"You're up rather early," The Doctor walks up next to River and kisses her on the cheek then flips a switch.
"I suppose, or you're up late," She walks away from him, much to his confusion.
"What's wrong?" He innocently tilts his head to the side.
"Nothing."
"Then where are we going?" He sits on the stairs and yawns.
"The store." She walks to him after they land.
"Shopping, are we River?" He stands and walks with her to the door.
"Not exactly."
"You're not stealing anything are you?" He squints his eyes in suspicion at him, she isn't smiling. The Doctor feels worried for some reason. River is mysterious but never this mysterious and he feels like whatever she's not telling him may be big. "Are you alright?"
"No." She sighs and his eyes widen at her.
"What's wrong, are you hurt?" She laughs a bit at this, and rubs his arm to comfort him.
"Sweetie, it's my time of the month," The confusion on his face has not faded. "My friend is in town?"
"Who's your friend?" She looks at him for a moment and then realizes he really has no idea what she's talking about.
"Doctor, I'm on my period."
"Your what?"
"You're serious, of all the girls you traveled with you don't know what it means for a woman to get her period? You know more about time and space and different universes than you about human anatomy?" She laughs a bit and decides to explain. His facial expression fades from confusion to pure horror at the word "blood".
"You bleed where?!" He steps back, mortified.
"It only lasts a few days, it won't kill me, and I don't usually get cramps that are too bad. Nothing I can't handle I suppose." He still looks at her oddly which makes her laugh.
"How do you stop it?"
"You don't stop it, sweetie. But I'm going to the store to get tampons." The look of confusion once again returns to his face. "Tampons are made to be inserted to stop the blood from coming out for a little while."
"Inserted where?" River gives him a look and then he understands. "Oh."
"Alright, well I'm going to go get what I need and then we can-" The Doctor kisses her, interrupting her sentence.
"I'm sorry you have to go through that." His hands now resting on her shoulders. "We'll go get what you need and when we get back, we're not going anywhere. We're going to spend the day in the TARDIS so you can relax, yeah?"
"Thank you, darling." He nods and they leave the TARDIS together.