Don't feel sad. Just make yourself gently available. If he's had a cold, he'll struggle to breathe while feeding. This is more likely to resolve with him still feeding than not.
DS recently (at 14mo) reverted to exclusive bfing during/after norovirus and my supply adjusted immediately. In fact after a week of non stop feeding, he went back to a normal routine and I was engorged for the first time in a very long time. But they then adjusted back down again quickly.
Over 24 hours your supply shouldn't be significantly impacted. Most mums after finishing breastfeeding can still produce milk weeks/months later.
It may be that he comes back full throttle after he's got over this cold/temp and will be sucking for England which will boost your supply again. It could be (don't cry) that he is slowly weaning off you I have known this to happen amongst my BF group, when illness prevents them from nursing and then they don't really go back to it. Obviously this really sad for the mum, but it has naturally happened which is how I'd want my dd to stop.
My dd had cut right down and has been teething recently so went off food and was all about milk. Within 24 hours my supply adjusted for her over 3 days, then she went back to 2 / 3 times a day and I had engorged boobs for the first time in months (dd is 16 months).
If you are worried, try pumping / hand pumping to boost supply.
Hopefully someone else might be able to give more experience on this
DS is 14.5 months. Over the last couple of months he has reduced down to 3 feeds a day, morning, afternoon and evening, although depending on what we are doing he has sometimes not had the afternoon one (he used to feed 1/2 times overnight but is currently sleeping through.....touch wood, please god etc etc)
Anyway, he is ill at the moment, cough, cold, temp, v out of sorts, and has been off feeding for a couple of days. Yesterday he had 3 feeds still, but not substantial ones, and today he fed briefly this morning when he woke up, but refused in the afternoon and also before bed (which has NEVER happened before!) He is also showing a distinct preference for my right boob, so the left one is not getting much of a look in at all!! How long would it take to actually loose my supply? How would I know? And could I loose it from 1 side but not the other?