It's hard to make changes like that in your nursing and in his cycle. Your breasts are used to double side feeding - that's how they produce, you trained them that way. So to switch to single side feeding, you will need to feed more often because he isn't getting the same amount of milk from one that he was getting from two. Make sense? Some women's breasts will "understand" and change - to make more on one per feeding. Some women's breasts will think, "hey, we don't need to make as much" hence the night wakings and more frequent feeding.
Other thing is that you are at a very distracted phase. Babies need quiet places to eat around this age, for you not to talk to them, etc. Since he isn't eating enough during the day, he is naturally wanting to eat more often and waking for feeds. Just odd timing with trying something new.
Maybe go back to your double side feeding (I have d-s-f since 3 months just fine), try to feed him straight off his nap when he is still sleepy before leaving his quiet room, and let him eat as often as he needs during the day to up your supply. If he isn't eating properly, do you have a pump that you could pump off your milk? At least your body will say, "make more!" that way.
