He makes up some "doctors orders".

"Thanks for giving me a ride, Matthew, dear, I appreciate it, really. I just don't see why it was necessary. I feel fine!"

"Yeah, I'm sure you do, but the doctor had a lot of specific instructions that need to be followed, and he left me in charge of them so that you wouldn't have to remember them all yourself."

"Oh, how thoughtful! What were these instructions?"

"Some of them are a little...personal."

"That's okay, honey, you don't have to be embarrassed. You're family, and if it's doctor's orders I'd best know what they are."

"Well, for starters, I'm supposed to administer what he called 'manual mammary manipulation and simulated nursing', every evening."

"Oh my! That does sound...personal! Does that mean what I think it means?"

"I'm afraid so, Mom. I wish I didn't have to, but the doctor said I have to grope, er, I mean 'massage' your breasts, and even suck on your nipples! If I don't do it every day, your condition might get worse!"

"Oh dear!" Margaret blushed a deep crimson at she thought of her 20 year old son massaging her breasts and sucking on her nipples. "But you're my own son, isn't that a little...wrong?"

"That's what I thought, but the doctor insisted. It has to be a genetic relative or the treatment won't work correctly."

"Well, I guess we have ****. Shall we get it over with?"

"I guess, so." Matthew said, trying not to show his excitement as he watched his blushing mother unbutton her blouse. Underneath she revealed a heavy-duty, no-nonsense cream-colored bra. She let out an audible sigh as she reached behind her back and unhooked it, releasing her two huge breast. They were round and creamy white, with faint traces of blue veins and big pink nipples. They were each the size of a spaghetti squash, and hung heavily over the bottom of her rib cage.

"Okay, just, close your eyes and pay attention to any physical sensations you have--especially any, uh, sexual arousal response. It's perfectly normal, but we need to keep accurate data."

With that Matthew took one giant breast in each hand, lifting them gently to feel the weight of them. He let his thumbs drift over her nipples and move them in circles. He groped and squeeze, tweaked and pulled.

"I'm uh, I can't believe I'm saying this," his mom said with her eyes tightly closed, "I'm beginning to feel aroused."

"Describe what you mean, please," Matthew said, as he took his mother's hard nipple into her mouth and began to lick and suck on it.

"Oooh," she said, "that feels good. I mean, um, I'm feeling warm, uh, down there. And I'm getting wet. I feel like I want to touch myself. To uh, how should I say it?"

Matthew gave her nipple a final suck and answered before moving to the next one. "You feel like masturbating?"

"Oh, this is so embarrassing. Yes. I feel like masturbating. Ugh, or even better, being filled up and fucked by big, hard...I mean, I'm growing wet, and I feel a desire for...for intercourse."

"The doctor said that strong sexual arousal is a natural side effect of this treatment--you may pleasure yourself during the treatment--and orgasm will amplify the benefits," he said while rubbing his saliva around her nipples with his thumbs. "But it's important that you never orgasm between sessions."

Matthew had barely finished speaking when his mother plunged her hand down the waistband of her panties and began fucking herself furiously with her fingers. He felt his erection pressing uncomfortably against his jeans. He checked to make sure her eyes were still closed and unzipped to free his hard cock.

He continued to suckle and massage her breasts with one hand while he slowly stroked himself with the other, until he felt her quack and shutter with orgasm.

"Oh god," she panted, "I'm sorry you had to see that, honey."

"It's all for your health, Mom. Nothing to get embarrassed about. Now get down on your knees I need to administer a special lotion to your face and breasts. It's very potent, so be sure to keep your eyes closed."

She dropped to her knees, her eyes tightly closed.

"Good, tilt your head back slightly, and lift your breasts and push them together a little."

Matthew jerked himself off until thick sticky ropes of cum hit his mother's cheek and chin and drippled down onto the perfect shelf of cleavage she'd formed for him.

Matthew tucked himself away. "Perfect, now rub the lotion into your skin, making sure to get your entire face and the entire surface of your breasts. Good. Now, you may open your eyes and lick your hands clean."

When Margaret finished licking all of his cum off of her hands, she looked up into his eyes, a little tearful.

"Thank you again son, I know that must have been horrifically unpleasant for you, having to touch your mother that way and watching while I...did what I did. I know not every son would do so much for his mother, and I just want you to know how much I appreciate it."

"Oh Mom, you know I would do anything for you."