"Great, now... Pockets, pockets, pockets." In harsh contrast to how gently the Doctor had picked you up, you're haphazardly thrown all about in her grasp while she rifles through her clothes for somewhere to put you, scatterbrained as she was.
"Hmm," she begins thinking aloud. "Only got one pocket in this coat and it only fits my sonic and my psychic paper, besides, can't have you messing with that... Ugh, I've been meaning to add more pockets. Never had this problem when I was a man." Then her frantic searching ceases; she's had an idea.
"Oh, I know..." is all she prompts you with before pulling the waistbands of her trousers and pure white, unisex underwear forward and releasing you from her grasp before you can get out so much as a "whoa, whoa, whoa, hang on a minute..." You're caught by the hammock of her undies, and tumble down the steep incline of smooth fabric until something stops you.
You feel a squishy, warm wall against your cheek and, once you regained your bearings, you realise that you're dwarfed by none other than the Doctor's fanny. You're speechless; you can't help but literally gulp, as if you were face to face with a kaiju. It turns out that two hearts really was all that separated human and Time Lord biology.
"How's that for ingenuity?" the Doctor compliments her wit, oblivious to any etiquette, snapping you out of your trance. "Alright, now. You just wait there while I find a way to get you back to regular size." She doesn't wait for a response, rather her massive face gazing down upon you is shut out as she allows her waistband to fall back into place.
"I'm sure I'll figure it out in no time," you hear the Doctor say to herself through the muffle of her clothes as you're sprung into the her crotch by her undies too returning to their regular, figure-hugging state. What little elbow room you had down there goes away, but then momentarily returns as the Doctor peeks in once more to say one last thing: "And try not to move around so much."
1) Your struggled movements against the Doctor's crotch inadvertently start getting the her off, something she hadn't foreseen due to being fairly unfamiliar with being a woman.
2) You're near-enough entirely immobilised, therefore unable to remind the Doctor that you're down there, her mind wanders and she forgets that you're there.
3) You're able to move but the Doctor can't feel it and so still manages to forget about you.